You can get generator prep which includes everything but the genset.
My 2017 Eagle 293RKDS I ordered with genset prep or dry camping package as Jayco called it. I have since installed an Onan 5500. I'd never own a 5th wheel without an on board generator. But we field camp a lot.
2017 Eagle 293RKDS, factory ordered, lots of mods and upgrades.
2018 Ram 3500 crew cab long bed SRW diesel 6spd Aisin 4wd Tradesman.
B&W Ram puck 5th wheel
Mopar wheel to wheel steps