It is necessary to have a generator in a 5th wheel, I know some have them some don't. We are looking to go to a 5th from our class a and we really don't use ours a lot now.
The dash air does significant cooling in a Motorhome while traveling down the road. A fifth wheel doesn't have that advantage. I'd lean towards having a portable Yamaha 3000 Sieb with a remote start kit on a rack at the back.
