Cooling topper
Never done it, but it would seem to me that you need a 12 volt fan, an RV roof vent and wire up a powered vent. Open the windows in the topper if you have them or cut in some side vents to create a cross flow.
I had the same problem. I have a 12 volt fridge that i use for work during the summer. I ran the wire through the back window and just plugged the fridge in with the lid up. It actually did a pretty good job of cooling the topper for my pooches.

