You could adjust the price based on size. 

Personally I’ve never done the binder method and made a tenant multiple rent options, I’ve just set the new rate and sent it out to them via certified mail with a start date of the new rental amount 2 months out so they have time to move out if they want to.

Some details, 25 year AM, 10 year fixed then converts to 5 year adjustable, 6.91%, and no pre payment penalty. 

They also referred me to a public adjuster at the same time.

Schedule a time to visit the rental and do a walk-through to ensure it is safe (no running water, temp adjusted, trash hauled out, etc.) and secure.

Next Step: Adjust accordingly.

I think I would make excuses or adjust the criterias just to make something work.  

Nobody wants an ARM (adjustable-rate mortgage); yikes - of course not, everyone knows you are at risk of forclosure!

talk to the dept of health first (records requirements etc), establish what upgrades/maintenance required, line up a reliable repair/handyman/type person, consult lawyer, and then make your offer, see if you can buy the land it's on via lot line adjustment (ideal scenario). a lot to be aware of, such as system upgrades or county code changes bringing in the requirement to add metered connections to an older small system, for just one example.Otherwise- owner doesn't want to manage, I doubt you really do either but could be wrong. 

(Father in-law was an insurance adjuster)