I don't know if your fifth wheel has slides or not but if it does here is something to think about in adding an air unit. My 36ft Prowler has three slides, two of which are in the living room. The window on the passenger side slide located near the rear of the trailer lifts up. I went to Walmart after measuring my window opening and put in an 8,000 cooling air conditioner by admiral, with remote. Fits right in the window and comes with little blocking slides that fill in the gaps on both sides of the air unit. Plug it inside the fifth wheel and combined with my ducted roof unit I am able to get temps in the 70's when the ambient temp is in the low 100's. of course you have to take it out each time that you move but it is a clean set up and does not look hokey. Not that that woulld matter to me but I have to live with someone to whom it would make a difference if it looked a bit red-necky (New word) Oh yeah, I think I paid less than $150 out the door.