A person with a property in year 1 or 2 saying they have $400 a month in cash flow means they are missing a key metric in the information they are giving you unless the deal was100% financing and the only cost they paid out of pocket is the inspection cost, appraisal cost, and closing cost.

You may need a construction manager (a guy a friend who is organized doesn't need to be a pro trades person but doesn't use or party) to daily boots on site be orchestrating who is on first and that no one steals your supplies.

It's nothing personal.

It all depends on what "too thin" looks like for you personally.

This is the main reason why a project would fail and that’s probably what it is when you see idle building frames in the landscape.There’s another version of that same risk when the developer uses the money from his first buyers for anything other than the construction like personal expenses for example.

If  you have the contract drawn up and signed, unless you change the terms (eg want money back and he says no), he can't go and sell it to another person...if you follow the terms and conditions in the offer that he accepted. 

If you were trying to give personal advice or constructive critisim about something that is off topic than a private message would have been more... to use your word professional.

One group may be ok doubling up in beds and the others may be seeking a bed or even a bedroom per person joining.

Personally, I think the true appraisal is somewhere around $290k before addition of those bedrooms. 

Personally speaking, my long term rentals don't have any cameras that I installed.