I would not mount a generator on the bumper because of the bounce factor unless the 5th wheel came from the factory with a receiver. That is a lot of weight hanging far past the axles and personally I think it would just lead to problems.
But..... I will never go camping without my Honda EU3000i generator. I like to run the A/C while traveling so the camper is always cool. We also stay at Wal-Marts and truck stops when just trying to put some miles behind us when getting someplace.
I will be getting a new Copper Canyon by the end of the month and I am going to install a transfer switch so I won't need all the wiring you will see in the following links, but they might give you some ideas.
The forum moderator said these kinds of links would be ok, but if not, just remove them. If they get removed you can find the information on my website under RV -> outside tweaks -> generator wiring and RV -> other stuff -> Honda Generator cover
Thanks,
Bobby
Generator Cover
Generator Wiring