That's not really a full story so it's hard to say, but generally, if you don't feel secure or confident in the person you hired, you shouldn't have hired them.

Do nothing...the tenant isn't renting that area and has no right to dictate how you use it as long as it poses no security/safety risk to them. 

Sometimes it’s the smartest move to gain liquidity and to secure your position with your remaining properties.

I thought  @Elliot B. was talking about installing meters on the supply and return pipes for each unit and measuring BTUs there.

It was truly the wild west.For the same reason I said several years ago the price of houses weren't going to crash due to supply and demand and the supply being so low, I believe the same thing is going to happen out here.There was an oversupply of building going on 2 and 3 years ago out here especially on the bigger cabins.

Building out my portfolio with strategic, secure passively cash-flowing assets to continue to build leveraged equity.

Yes, up, it's simple obvious supply demand metrics. 

Visa and FinancingYou're correct that securing a mortgage might be challenging without legal status or a W2 job.

Real estate is going to be more rate and supply driven, than election driven.Equities will be election spurred(in the short term) but fundamentally earnings driven in the near term.

You may or may not wish to fix it since its likely too late to charge the last tenant's security deposit for it and also that it sounds so minor that people didn't even notice it right away.