I’m going to add a vote for the practicality of a yurt, even though I don’t particularly like them. Quick to erect, most effective use of space for square footage needed, easier to heat- with a woodstove in the middle radiating in all directions, feels roomier than it really is (helping you all to not kill each other in darkest winter), generally very easy to re-sell (as well as relocate on the property for a future guest house/air b&b/older kids new home). The cons would be- harder to insulate well, harder to create privacy for everyone, and they tend to have less airflow which can lead to mold/mildew problems.
Second choice would be to build a barn, or shop, since you’re going to need one anyway. The biggest hurdle there is deciding on location. But it’s still fairly quick to frame up and dry in, and then you can work on the rest regardless of weather.
I think mobile homes are possibly the worst choice. Yeah, it’s quick and maybe cheap, but even the best ones are poorly constructed with lesser quality plumbing and electrical. As someone else mentioned, the shape is inefficient to heat, and they lose value quickly; something you don’t need to worry about with a yurt or shop.
I hope you’ll keep posting here with updates! This is an exciting challenge in several ways, and what looks like a nice property for homesteading/permaculture.