I'm guessing you have considered this, but one way to get the benefits of rental ownership and still have intermittent access to your property, would be the Air BnB route.

I'd like something that's relatively cost effective, so central air is likely out of the question.Does 3 zones make sense?

We have a warehouse with no access to cool air coming in.

Train tracks, gun clubs, air strips, double-yellow lines, shopping plazas, school zones, flood zones, cemeteries, landfills, etc. 

Recently I have had several inquires about AIR BNB Properties. The concept is terrific, and I know several property owners who are experiencing great returns on their Air BNB Properties. There is an overwhelming deman...

At most a ductless fan will circulate air through a filter that might (or might not) help with smells.

There is some water damage from a built in air conditioner and the inside of the house needs to be painted,  carpets pulled,  wallpaper removed in the kitchen and a bedroom,  hardwood floors refinished,  and possibly the dated kitchen updated with new cabinets, appliances and counters.  

I felt like the heat loss study was such a pain that I should look into a central air and furnace system. 

   Wow, that seems way high to me. 117 houses puts you in pretty rarified air as far as RE investors goes.

Air b&b?