I'm about 275 miles east of you along the 40.
I use 6 foot t-posts 25 feet apart. I'm eternally broke so when i can i wiil put another post between them to make it 12 1/2 foot apart.
I build as i have the money.
Find a tractor supply store for the price. Don't buy the cheapest barbed wire, you will regret it.
A good time to pound your posts into the ground would be when it's wet.
Palo verde grows along the freeway west of kingman. If you want seeds now, go to yucca and find the honolulu club. South of there on the frontage road.
If you have a drink at the club let me know if you survived.
I use 4x4s for my gates. They don't handle the weight well so i cemented them in place.
One way to keep people out of my driveway was to put up a gate but without fencing.i even chain it.
They get the idea.
On my long perimiter fencing i didn't use any wooden posts. I just braced the corner post with another t-post.
I have a fenced off area in the middle of my property, sort of double insulation should a cow get in. That square has 4x4 posts at the corners. It holds up better than the perimiter fencing.
I have a ten hour drive from LA. Sometimes i wish I'd looked around your area.