If you are selling for 1M after closing costs you could purchase two 500k properties in your exchange and own one cash and a mortgage on the second.

If the drywall cracks in the next year or two, or the doors start to stick, then you likely have a larger settlement issue going on, and will likely need to call a foundation repair contractor. 

Just sell and pay off that loan or two.

Two of them decided to move out in December without informing me.

Two years ago, I had to deal with a 1,500ft townhome with a horrific cat odor.

It's not quite as easy as renting out two sides of a duplex, but with the right marketing and management you could rent out the extra unit to supplement the mortgage payment. 

It seems clear that it is in lieu of a 1031 since UPREITs are under sec 721 so the two don't mix.

I have two kids in middle school and I'm trying to get myself ready to retire by 55.

I'm living in one unit and the other two are rented out. 

Best practice is to keep one or two payments in reserve from the buyers down payment for such instances.