Your son will be forced to sell or refi, and I bet you that this deal can't handle that situation. 

Or buy and force appreciation or buy and paydown debt with cash flow..

This also protects my downside risk because I could very easily lower my rents if I had to in a market downturn and compete vs. being forced to sell because of losing money. 

If I had just bought this property and could force some appreciation, I could refinance and hopefully extract that equity within a year, for example--but since this house is paid off, refinancing would introduce a new mortgage payment.What are the options here?

While we were a bit over budget and slightly over our projected timeline, we were still able to force appreciate the property by $100k.

Our contract is enforceable, and I can sue Don to force him make the payments that he agreed to make. 

Clearly identify what you want to achieve in real estate and use that as a guiding force throughout your journey.

Your park name has now landed on someone's government desk and you will eventually be forced to answer a lot of uncomfortable questions. 

A PMC can get a bad reputation really fast and be forced to use only the WORST contractors that are unreliable hacks. 

I am currently serving in the United States Air Force, so as a military member, I will be moving around during my career.