Our 5th wheel came with "partial" generator prep. It has a 50 amp twist lock Marinco receptacle mounted on the front of the 5th wheel along with an automatic transfer switch. We use a 50 amp twist lock to 30 amp male adapter to plug into a 30 amp extension cord that then plugs into the 30 amp receptacle of 2 each Yamaha EF2000is generators running in parallel in the bed of the truck. With this arrangement, we can run 1 15,000 BTU air conditioner while on the road to pre-cool the 5th wheel and also power our residential fridge that would otherwise operate on battery/inverter power without the generator or shore power.
Rusty