There was a company that build a batch of EV E450s to use for Long Beach public transit. It works ok for stop-and-go use, but the physics of pushing a brick wall through the air don't lend well for EV use on the highway yet. For a viable EV motorhome, the efficiency of the chassis and aero need to be dramatically improved, and even then, a lot of batteries won't go far.
The Thor ACE is one of the worst designs for reducing drag because of the "forehead". The Thor Vegas and Axis are the best, actually allowing Thor to meet greenhouse gas limits for a Class 3 chassis.
You ace with it's Cd around 1.3 and frontal area estimated to be 86 sq. ft, would require 160 kW (including ~10% for driveline and accessory losses) to drive down a flat highway at 60 MPH.
The battery back from a Tesla Model X has a capacity 100 KW/hr. You'd only be able to drive your motorhome around 37 miles before needing a recharge. Assuming no headwind, hills, using heat etc.
For a usable range, you would need about 10 Model x battery packs. But each one weighs 1200 pounds. And your existing cooling system might not be large enough to reject the heat of 10 of those packs charging simultaneously. Using a 240v charger (to utilize campground power), you'd need 120 hours to recharge your battery bank to drive another 370 miles. Plus you'r need a 2nd pedestal to power the house while your chassis charges.
