This was a 3bed 1bath that needed everything besides a roof.

I saw an ad for EverSeal offering a 50-year warranty for their flat roof system.

The second one needed a full roof.

People are often lax when it comes to their revolving credit but not with the roof over their head.

Much of real estate investing is being able to sleep at night and I imagine that's very difficult to do if you're worrying about if your $X00,000 beach house still has a roof the day after a Cat 5 blew threw and a Cat 3 pending the following week.   

or “Is it legal to build a treehouse on a duplex roof?”

You don't think they will want their insurance, which I assume they've been paying out of pocket for many years since the house was build and owners never paid, to cover the cost of a new roof and fix the leak which appears to have been there since the house was built?

I started with an afternoon every other week, which was changed to an afternoon every week.So I put issues into 3 buckets: emergency (a pipe is leaking), within 24 hours (toilet running), and non-pressing (a door is not closing on its own), which is where most things landed and are handled that way.

Anything above that needs to be justified - roof replacement, parking lot repaving, etc. 

I would suggest just that, house hack a 4plex for cash flow, and save for your second creative finance deal and grow from there.The idea here is you should be paying zero for your roof (or close to) before buying a second property.