Considering the whole point of a motorhome is to get away with it all, I'm not quite sure how useful an all-electric one can be, unless you want to limit your excursions to a fairly close area from home. There are many sections of this country where even Tesla's network is sparse if non-existent, and often those are areas where people tend to want to camp.
What would have been better is a PHEV motorhome, allowing you to drive on electric in traffic (where an ICE has the worst efficiency) and have a liquid fuel for long distance travel and quick refueling. When you get to your campsite, the motorhome's batteries (hopefully recharged enroute) can then be used to provide campsite power, limiting if not eliminating the use of a noisy generator.
Blue Ocean 2012 Leaf SV, lost that 1st bar at 34 months/26,435 miles. Lease returned 2 months later. Final LeafStat figures: 225 Gids, 17.44 kWH, SOC 91.89%, SOH 82.36%, 69.49% HX, 54.57 Ahr, battery temp 61.8 F.
Now driving a 2015 VW eGolf SEL.