I can think of only two things that rise inexorably and never fall - college tuition and health insurance costs.  

@Luke Chung Congratulation on the property and the health of your son!

There is VERY limited housing around here, so people who have housing vouchers can hardly find a place to move into and those with mental health are essentially screwed.

I suppose this could happen with any seller regardless but I am also concerned given his age and ill health, what if at the time of purchase his interest in in probate or held by surviving family? 

Only human intervention would figure this out.

To cover myself, I added the following provision to my lease..."... when needed to water the grass, Tenant agrees to allow use of their paid water to maintain lawn health and appearance as needed."

Just a thought, but keep in mind the board is made up of humans and they all have wants and also have reasons they they don't want to be in a rental community.

Again, not mandatory but seems to be more common as the concern increases about the health issues related to cesspools.Mark

The other part of this puzzle is his mental health.

It is more an effort to humanize your offer.