I would be shocked if high-end rigs like those didn't bring their own electrical services with them (IE on-board generator) and a really big fuel tank.
There's three channels I watch on youtube with young couples boondocking in Class A's. The biggest concern they seem to have is burning propane too quickly, followed by water. The one group gave their borrowed RV back to the manufacturer and bought a boat, the other group keeps talking about trading down to a 5th wheel, and the last couple is selling their A and bought a tiny Airstream.