Primary bedroom has large 3/4bath and walk-in closet. 2 more bedrooms are on the main, large upper bonus space and full bath.

All rooms have a ceiling fan and I allow them to have portable/window units (they pay all utilities).

We typically reserve a closet, garage space, or something internal to the home that is on a keypad lock so we don't have to worry about lost keys.

I have a property built on a crawlspace that is having minor mold issues in the closets.

The third option would be providing a portable unit, which may be an option.   

Sometimes adding a closet to a "bonus" room is just the ticket to turn a 1 bed / 1 bath into a 2 bed/1 bath!

Part of our bathroom rehab included cutting into the closet in a second bedroom, moving the sink and vanity, and installing a door between the biggest bedroom and the bathroom.  

I'm in the insurance industry as well and I preach to the young guys in my office to save and invest their commissions instead of buying $200+ shoes for their closets or blowing it on nonsense.

During the due diligence process (about week in) one of the tenants reached out to complain about the heat so I had my mom purchase a portable unit for them to use the next day.

Does the room have to be completely closed off and separated from other rooms, and does it need to have a closet with a door?