You may not 1031 into a REIT however there is a product similar to a TIC called a DST (Delaware Statutory Trust) that qualifies for 1031 treatment.  

I'm aware its not a long term solution to provide the vent boxes.  

What is the solution?

It seems like you've analyzed the deal and have solutions for most of the issues.

I'd keep it monthly, just do whatever work out you want to do to get him current and stick to your current monthly terms to deal with him if he gets late again and then consider a guaranteed solution if that keeps happening, which is eviction, Screw cash for keys and all the work arounds you're looking at.

But maybe one short term solution to your question would be taking a contractor through the place with you?

This is not a one size fits all solution.

It is a commitments that I will never propose a solution to someone's problem until I fully understand the problem.

DO NOT DO BUSINESS IN MISSISSIPPI WITH GLOBAL FUNDING COMMUNITY DEVELOPMENT, LLC.....based in Florida building under Go Zone in Mississippi....beware....they approximately 5 companies setup that funnel money into Global Development.....flips are involved.....Dream Developers, LLC, Land Solutions, LLC, The Squad, LLC, among others.....someone buys the lots under Land Solutions employed by them....get the picture now

Window companies can now drill a couple holes iinto the outer window, fill the interior with solution, and seal the holes so the window will dry and clear up internally.