I have been researching fifth wheel toy haulers for a couple years and the best one I have found for me is the Grand Design 351M but am wanting to set it up with a Cummins/Onan diesel 6000 watt generator instead of the 5500 watt gas unit that is offered for it. All my toys are diesel, except my two stroke golf carts, plus my tow vehicles are diesel. I do not want the inconvenience of dealing with gas for the generator when nearly everything I own on the farm is diesel powered.
I want this unit: https://www.granddesignrv.com/showroom/2019/toy-hauler/momentum/floorplans/351m
and this generator: https://www.ebay.com/itm/Brand-New-Cummins-Onan-6-0-HDKAH-1044-Diesel-Generator-RV-QD-6000-Quiet-6kW-/232837680571?_trksid=p2349526.m4383.l4275.c10#viTabs_0
Another thing you will need to consider is your tow vehicle. You will need at least a 3500 for most fifth wheel toy haulers. I have a new 4500 on order because I like overkill and need it for my farm and business anyway.