I feel that most handling issues are a result of what the motor home builder has done to the cab and chassis and not because of what the base vehicle builder has done. I don't believe the van builder is putting out a vehicle that as it comes from the factory, can't safely carry the maximum load it was designed for.
The MH builders try to put as much as they can into these rolling houses. Whether they're putting too long a box on too short a wheelbase, or screwing up the weight distribution of all the goodies,the lousy handling is their fault, not the cab builder's.
In my case I've had 3 class Cs. I currently have a 1997 Coachmen E350 24'er and a 2014 Itasca E450 32 1/2'er. They both handle quite well and no changes over stock were needed to get that good ride. My worst riding class C was a 1995 22' Four winds on a Chevrolet cab and chassis. It tracked OK, but it really leaned while taking corners, even when new. I also should mention that the 5.7L engine was barely adequate for that small MH, while the V10s in the other two provide more than enough power.