How would I know the sewer or foundation isn’t rotting out below the building, or that there’s going to be a huge assessment to replace siding in the next few years?  

They may be pressure treated, but even pressure treated is susceptible to rot over time. 

Is it possible to remove the upper cabinets for now and let the drywall dry and leave the re-drywalling until she's out? 

They pull any moisture they can get out of the air, so if there are any small cracks or openings to outside air they will just continue running, filling up their tank from the moisture in the outside air and not working efficiently at drying out the space you’re trying to dry very well.

Believe it our not, we still have a lot of success with Craig's list, though not sure if it'll work with newer build assets.I would try to build relationships with businesses that your residents use, such as pet stores, restaurants, dry cleaners, etc.

It's kind of like a a guy who gets really excited about something touch really really fast and you can't understand a word he says sometimes you have to slow it down  I've also found that I'm not saying he is but I've also found that in my life I'm 61 years old a lot of hucksters do the same thing  because they know if you show energy and excitement in a presentation more people will sign up then if you're dry as a bone

Major dry rot/pest issues or perhaps knob and tube wiring would make me hesitant as well. 

Bad PMs in bad areas because they suck them dry with fees.

Outfit the space as turnkey for an appropriate business (smoothie shop, dry cleaning substation, etc.) and sell the “business” with a small down payment, receiving a monthly payment for the business payoff + rent/3.

When discretionary spending dries up, travel typically plumets.