Most actually go a lot further than that. We're in the process of building right now with a large-ish builder + separate lender. We can't even do the painting ourselves, the mortgage company requires that we hire it out.

I'm short on free time anyway so it's not that big of a deal but finding a lender that would let you do everything is probably a bit tricky.

Finding a contractor who will take a few bucks under the table in exchange for putting their name on the paperwork and checking your work prior to code inspections is not usually that hard.

Those are both cheap and easy to get though.