I seriously doubt the person built those things by himself. If he did, then I bet there's no electricity or plumbing, and it would've just been better to buy actual trailers as he could have a fleet of them delivered in a few weeks rather than spend years of hard labour building them himself.

I would imagine that fund-raising would work regardless as long as you're showing that this is a charity thing.

Of course, I bet any sort of joined home would be illegal there as it stands. Zoning laws are the absolute worst in most western countries, making anything but an expensive and space wasting single family house illegal to build in most housing zones. It's the single biggest reason why housing prices are so out of control, and will likely crash taking 30% of the entire nation's retirement savings with it in the next decade or so (since most people who buy houses and bet everything on being able to sell it at a massive markup for when they retire).