There is an exception in the 121 primary residence exclusion that allows you to get a prorated amount of the gain tax free if you have lived in it for less than a year but have to move for a job, or medical related issue. 

Medical debt?

In Columbus, where I'm located, there is a mix of a tech and medical boom.

My commercial top choices are storage, medical offices, or retail. 

Since thee are exception for being forced to move for medical and job reasons there are probably exceptions for military moves.

I have seen it happen with rental properties car accidents where people are put in the hospital and rack up $700,000 in medical bills like that!

There is a lot of good information in the following thread.https://www.biggerpockets.com/forums/81/topics/145073-doctors-note-for-cats

Most people have less than 3k in their bank account and basically are one blown-transmission, medical emergency, or roof leak from being broke yet some freaking guru want to you to trust them and spend your VERY LAST on their program.

Does anyone want to bet against me when I wager this tenant is going to do a couple minutes of googling and this dog is going to magically transform into a medical device and be deemed an ESA. 

Studios / 1 BRs are the most popular for travel medical professionals.