The 31-foot Class C in my signature has a 218" wheelbase. The front axle has 4600 pounds front and 9300 rear. That's with no slides but fully loaded for travel with crew aboard.
A longer wheelbase shifts what would be rear axle loading to the front axle. If our wheelbase was say a foot shorter, it's likely the rear axle would be at, even over, full load. The Sunseekers have a max loaded weight of 14500 pounds, so FR is transferring some of the house weight to the front axle. Makes complete sense.
If the Nexus Phantom is the 32SC, it's a Super C with a max loaded weight of 19500. Also a much more robust chassis than an E450. Totally different animal than an ordinary C. Probably turns tighter, too, with a steeper steering "Cut."