She said there wasn't much stuff whic I agreed because I visited him a couple of months ago to do a routine check up on the condo and found out he had no furniture and sleeping on a air mattress.  

If they are looking for a person they can look in a closet or under a bed but they CANNOT look in bags boxes under the mattress in your dresser etc....

And they could audit her to see if she spent it or just stuffed it in her mattress :-)

I tried the "cash under the mattress" approach, but my bed was feeling kind of lumpy, so I decided to stick the money in the bank. 

Our apartment complex had a policy packet that was 16 pages,, included everything , also had a page with moveout cleaning charges like clean the stove was $125.00 , missing blinds were $35.00 for window, 85.00 for patio, clean window were $15.00 each for example.It gave noise requirements, where to dispose of trash, what was acceptable for trash, and listed charge for any large items left like couch was $50.00 to dispose of, mattress $25.00 box spring $25.00 so we were covered if they put any large items out.It covered roommate changes to lease, what a lease buyout fee was, how to pay your rent, how to give proper notice, late fee charges, charges to change lock,, how much lock out charge was to come and open your door. 

Successful companies and individual investors never hesitate to liquidate to cash and go the the mattress while waiting for buying opportunities. 

People are floating their stuff on air mattresses and in fridges.

Their parents will pay for any furnishings, or they'll just put down an air mattress and only sleep there.  

You don't necessarily need to go that far, even a 4-6" "topper" of blown cellulose will greatly reduce air leakage into the attic & that's what you and your tenant both want.  

LolI didn’t know you can rent mattresses!