I'm actively a broker & property manager and have dealt with tenants in this category, they know how to play the game better than most. 

That's for single family and small multis and if that's your game then that's good. 

I know I need to up my game and start investing if I want to make a dent in those bills.

Decide which game you want to play.

Normally builder will pay cash for the lot like i do that their skin in the game..

Money is expensive to borrow, and prices are high, and there is a lack of inventory, and there is little expected to change in the next year.The take away from that might be that you need to realize that real estate is a long term, cyclic 'game'.  

DSCR Loans are typically great for STR purchases - however, DSCR Lenders are going to require at least some "skin in the game" - so won't be able to have a 2nd lien for the down payment. 

I think if we know what you want to achieve we can reverse engineer your ideal "path"@Justin Kane makes a really good point on the scalability of the larger MF game. 

It's like a chess game... move and counter-move... think three steps ahead.Lastly, keep all communications with your tenant and her "guest" (now unauthorized occupant/tenant) in writing from this point onward, or have a witness with you if you talk to either of them.

It definitely helped us game plan how to fix this.