My fifth wheel has the fantastic fan above our bed. It works great cracking a window in the back of the trailer and letting the fantastic fan draw cool air through the trailer at night.
I would definitely not be able to mount a real ceiling fan. I can reach up laying in bed and almost touch the ceiling.
I can't believe folks put air conditioners just inches above your head in the fifth wheels but alot of them do it. I'd get head cold for sure with an air conditioner blowing directly on me while I sleep hehe...
The best small portable fan we have found to use around our trailer was one of those 10-inch O2COOL 120AC/12VDC/D-CELL battery fans (WALMART-LOWES-AMAZON)... they work great for us.

ALot of folks are looking at using the portable air conditioners now. They sit close to a window and have ducts going to the outside through the window. Folks really like them... All different sizes...

Roy Ken