I don't have a 5th wheel, but I have an old Honey, whose on board generator must have shot craps a long time ago and was removed. Since the A/C won't work without shore power or a generator, We put a rack on the hitch ( oh when pulling hubby's toy trailer, it sits bolted on the tongue to that) and we run the shore power cord around the side of the MOHO and down to the generator to plug it in. The cockpit A/C just got fixed this year before we ventured out into the desert area this summer, but even on as small as a unit as ours, the cockpit air is not enough to cool the rest of the unit down. It looks like the previous owners must have put curtains up between the cockpit and the rest of the house to keep the cold air in front. All this to say, we haven't had any problem with our set up as long as we remember to shut the A/C off before we turn the generator off to fuel the MoHo up.
Martha (AKA RVM45), Bob, and Bess the Border collie
22'Honey Sportscruiser on a 1988 Ford Econoline.
Sometimes towing a powered Parachute.