I'm in the process of adding a onan gen to the front compartment on my FW, it was not 'gen ready'.
I found an Onan 7kw gen (120v only, GAS) that needed repair (a pulley and a belt)
got the compartment floor cutout template
had the enclosure made
need to get the propane conversion kit for the generator (santa let me down this year!)
and an Automatic transfer switch. Then run some wire from the front compartment to mid rig where the shore power enters the rig.
Onan makes a wireless controller, EC-30W, the receiver just plugs into the genset. Then you can program it to turn on at a particular temp, avoid campground blackout times, ...
I'll still have over $1000 by the time I'm done.
propane kit = 250
EC-30W = 550
ATS = 220
enclosure = 150
wire = 100
gen + repair = 250
I have tested the gen (on GAS), running all the systems at once, both A/C units, microwave, coffee maker, and a hand held hair dryer. and it does great.
edit: propane conversion so I don't have to carry additional fuel source, and is less low use maintenance than gas (which will gum up)