That will dramatically change the nature of the wholesaling business with the legal compliance factor that agents need to comply with.

The accounting has been an absolute mess. I

If the seller is trying to avoid legal issues with the city for illegally operating a property I would get out of that.

And when you do a lease for MTR, you'll need to put that in the lease in case they stay through high season, spelling out exact prices for each calendar month, so there is no confusion and it is legally enforceable. 

Purchase price: $330,000 Cash invested: $15,000 Legal 3 Flat (that was not for sure in the beginning).

Is this even legal?

Here in Michigan you need to be licensed as a real estate agent or broker to be legal.

One block may be legal, the next block may not be.

An LLC is useful for two things: anonymity and legal protection.

You definitely want a legal agreement that's forecloseable, getting as much front money as possible so that you're not just in a lurch with nothing if/when they default, and you should get better interest terms for "being the bank" AND I would qualify the buyer just the same as if they had to go to a bank, because you want to know who your partner is in this deal.