We have never owned a Motor Home. We have owned 5 RV's including 4- 5th Wheel Trailers. The last three came equiped new for, wired for, but not including a built-in generator. We did not order a built-in generator with any of our RV's, including our Monty 3750FL that we own now, although it was available and the Monty has a special Generator compartment built in. We use the built-in Generator compartment for extra storeage.
I have always believed that since we pull our RV's with our truck, it is most efficient, most cost effective and much simpler to have the generator on the truck. We use our generators, on the truck, with other things besides the RV power on our ranches also.
With our Monty, since the Marine type cable socket is on the rear for shore power, I just permanently installed a cable from the rear to the front of the Monty, through the Undercarraige, so that with the generators in the truck all I have to do is start the generators, still in the truck, plug the parallel generator socket into the cable at the front of the trailer, and we have power. We don't even have to unhook the truck or run a cable for power. With the truck unhitched from the trailer the Yamahas are just set on the groundf under the trailer, with the cable connected, if we need to move the truck without the trailer. I connect the generators to the trailer with a locking cable when the truck is not there.
When in an RV Park the Shore power plugs into the same cable socket as the generators so everything works the same.
To shut off power to go I just turn off the generators, unplug the cable, and we are ready to go. No moving cables, generators, etc.
For years I owned a 4000 Watt generator on the truck that was used with RV's with a cable as described above. Our last generator finally gave up after about 12 years use. I replaced it a year ago with two Yamaha generators, with the parallel connection kit. We like this set up much better than the single 4000 Watt Generators that we previously owned.
Our experience suggests that you might be most happy with a pair of Honda, Yamaha, etc., generators that can be used individually or in parallel as needed. They are small and light enough, quiet, to place and remove them from the truck or RV any time. They provide all the power needed by the RV and are economical besides being designed for the job. Our Yamaha's also come with a three year complete warranty that I am happy with.
Had the new, twin, generators been available the last time I bought the larger 4000 Watt generator, I would not have bought the larger single one. The two Yamahas are much better.