Bryant RedHawk

hau Patrick, If you fill out your profile on the control panel, we might better know where you are on the earth mother and that means we can taylor answers that fit your situation.
Since I have none of that type of information (look at my profile under my name to know what we need) I will give you some information about your ideas.
By the way, if you investigate a large area around your location and see no tree lines that  might be used for living fence, that can be an indicator that it doesn't work.
Especially if you are in Europe where such structures are still around from the middle ages.

Fast growing trees have the very real tendency to be short lived trees, or at least far shorter lived than the slower growing hardwood trees.

If you can get them two of the best are Honey locust and Black locust, both are very rot resistant, grow at a nice pace when young and then slow down as they get older and they both coppice well too.
The wood is one of the standards for wooden fence posts in the USA and other countries where they are growing (only the USA is the natural habitat for these two trees.
One other tree, the bald cypress is known for it's non rotting abilities and in swampy areas it is the prime choice for fence post wood.

Now, about the need to go deep, what is it that you are keeping in/out of the area you want to fence? That has a great deal to do with how deep a post needs to be sunk into the ground.
Surviving without water has a lot to do with your soil and the microbiome in that soil, most tress will need to have some water in the soil most of the time.
If a tree is living, it will be taking in water, no matter what you do to it; prune, coppice, pollard, espalier, etc. if it is living it will need water, so cutting a tree back to give other trees water availability, is more one of those "Only on the internet" types of thing.

Depending on your latitude, you might be able to use moringa, a nicely growing tree that is one of the best sources of protein for humans that is available.
The moringa might work fairly well to your needs and it can also be coppiced.

Redhawk

In the USA, going on contour generally doesn't work so well. On contour builds hold all the water until it soaks in at the spot it gathered against the hugel or swale/berm, the water doesn't move along.
By building off contour, you alleviate the "stagnation of water movement", the water can slowly travel and seep into the soil all along the construct, this also helps prevent any "man made spring" from a water plume developing.

On flat land (less than 1/2 degree of slope) the on contour will work ok, but you would still be better off if there was some water movement along the full length.

Most of the top 10 feet of the Sierra Nevada mountain range is fractured granite, roots can get into the fractures and they will continue to widen those fracture lines.
Now, if you are wanting to use a lot of fuel and effort, then what you are doing would be worthwhile except that making hugel mounds is not how to plant trees, the hugel will eventually collapse and the tree will topple.
When you want to plant a tree, you want a stable surface, not something that is bound to collapse. If you really want that extra two feet for the roots, you will need to use stone and mortar to build giant "tubs" for each tree to live in. A lot of work indeed.

Why not simply use the land as it is, plant the trees and keep them watered until they have established nicely at that point they will have roots anchored into the granite bed rock and you are good to go.
More important than the soil depth is what is living in that soil, all the trees you mention require mycorrhizae to flourish, so make sure your tree's roots have access to these fungi and then add a compost mulch to prevent moisture loss and add organic matter to the soil.
By the way, granite soils tend to be acidic, so do get that tested or buy a kit and do it yourself so you know the starting base line then you can check it yearly to see how things are changing.

Redhawk

We are still in the process of terracing both the front (south facing) and back (north facing) slopes, I am using rocks from the land and cedar logs closer to the valley.
Some terraces are 3 feet wide and they go all the way up to 8 feet wide depending on the grade where they have been installed.
Up on the ridge I can space the terracing at 20 feet wide and I hope to eventually get everything done (our place will be reminiscent of Machu Picchu).

Redhawk

While it is true that the slime molds eat bacteria, this is true of all fungi to, so it isn't a thing for worries.
I would take some of the slime mold and add it to the compost heap, you will be surprised at how much it actually helps plants.

I have used MG on fresh straw bales to give them a jump start into decomposing, it works for that quite nicely (and the food coloring lets you know where you have treated the straw already).

Sugar is not something to use for wild animals unless you are baiting them in to do them in.

Simple syrup is a great use for sugar just not so great for bees unless you are in a deep winter and their hive doesn't have enough honey to get them through, in that one case it is acceptable to feed the bees but it needs to be pretty thick, just like honey.
Several of my bee keeper buddies had to feed their bees three years ago (we had a freak hard freeze that lasted three weeks that year) and the feed we made up looked and flowed just like the honey the bees made. (I am a good watcher of work by others)
That was when I decided to never rob my bees, so now they do their thing and my fruit trees and other plants get pollinated, the bees like that I don't bother them I think, I can go around the hive and never get stung. (which could kill me)

Redhawk

yes that would work nicely Chris.

Generally Hugels are used to store water for the plants.
Living on top of a mountain as I do, they work very well, since most of the rains end up down in the valley except for where my hugels are located.
It might be possible to use wood to build a hammock (raised, dry-ish land found in swamps) but Paul would be better able to address this question than I.

Redhawk

Wow Diana, that sounds like almost swamp conditions.  
You might need to raise your beds another two or three blocks high and fill those spaces with soil to be able to get away from wet feet for your plants.
The symptoms you describe are rather indicative of the plants being drowned.
The conditions are almost certain to be anaerobic (hence the potato and onion rot) and you  have to get away from that condition, sadly the only way is to relocate the  gardens or raise the beds high enough to keep the roots up and away from the anaerobic soil.

It is good that you have late afternoon dappled shade so the plants don't have to deal with so much heat stress.

Redhawk

This has so far been a weird year but I have the feeling we need to get adjusted fast because it is likely to simply be the new normal.

Tomatoes are indeed a strange fruit to grow because you can get splitting from too  much or too little water. We have been growing them in straw bales for the  last 5 years and this is the first time for the troubles.
Is it possible for you to use a raised bed for yours? That might be at least part of the answer, to allow for better drainage of water away quickly but still have enough available for the plants when they need it.

The best things about bale growing are compost after two growing seasons with a lot of it already conditioning the soil below and they hold enough water to last for 5 days of 100 degree heat and 85% humidity (our normal summer conditions, at least that used to be the conditions), now that the warming of the planet has gotten to noticeable on the skin levels, things are changing rapidly here.

I'm going to run a trial on a mango tree from seed, since our winters have almost stopped having sub 40's temps I might be able to grow one and only need a cover for the winter weather should we get any.

Good luck with the tomatoes.

Redhawk

hau Golda,

If your tomatoes are splitting at the  stem end, you are giving them too much water. I would recommend you try adding some potassium and potash along with trace minerals instead of magnesium sulfate (sulfates yield sulfuric acid, changing the soil pH).

Most of the time tomatoes will ripen in a blotchy manner, especially if they are being given too much water and their nutrients aren't balanced.
Try adding some mycorrhizae to the plant roots too, that will attract the right bacteria and help balance the nutrients for you.

Redhawk

Our tomatoes have gotten so much water this year that we are preparing to rip the plants up and start a new batch.
We have averaged 12 inches of rain per month since January this year and several 7 inch days as well as the normal rains.
It has caused many vegetable growers here to abandon the initial plantings and start new crop plantings to try as salvage the season (for us it is May thu November).

Redhawk