@Jose De La Macorra sounds overly complicated and there are probably many ways this could go wrong: everything people have mentioned above like healthcare costs causing problems, unknown heirs or past business partners coming out of the woodworks with title claims... plus if he dies next week in a freak accident that doesn’t look great for you either if you benefitted financially from his early death.

Current condition of tanks and wells are unknown.

The answer to those two unknown and unknowable questions is what will determine if selling is a good idea, but under most long term scenarios where you are in a strong market and sound financial position with your property, holding has tended to win the day over selling. 

You are screening and putting people together who are unknown to each other.

Yep; "credit score, and how high your loan to value goes, type of property" are all likely to play a part - but unknown by me as to how much. 

The unknown is whether rents or property prices will rise faster.

I know that sounds audacious, but it's not an unknown strategy.

I just couldn't bring myself to just throw it into some unknown thing that was out of my control/hustle. 

By investing in a few different locations, you will be as protected as you can for any changes in the market.CONS: Unknown market.

The other bonus with AMEX is bonus rewards with various retailers, but that is an unknown that can't be banked on.