Sounds like a great low-cost way to get started!
Fantastic that you've got some nut/fruit trees already there, especially mulberry. Given the time-frame, grafting onto existing trees could be a real help to let you alter the harvest times or change the varieties to suit your preferences.
Looks like you're probably a 6b or 7a hardiness zone. Tons of options! I personally will be trying for a very wide variety of
apple cultivars; not exactly exotic or exciting at first glance, but it's such a versatile fruit with an incredible range of flavours, uses, and harvest times...
Beyond that, all the usual suspects... I'd be adding peaches for sure. Plums. Sweet/sour cherries. Asian pear unless fireblight looks like an issue.
A bit more exotic: autumn olive, good
chicken food and a nitrogen fixer even if you don't like the berries yourself. Excel fig, which apparently can set fruit in zone 6. Arctic kiwi, actinidia kolomikta
Beyond trees, berry bushes, especially canefruit that will do the work of propagating for you, would be high on my list!
As far as heat goes, it might be challenging to use microheat with 4 people... but the savings are pretty significant! My little trailer just has a propane furnace, which is not my favorite option by any means... but it's a 14' trailer, and like yours has an insulated floor, so it doesn't take much to heat. I'm hoping to get by with bodyheat and a good sleeping bag most of the time.