John,
Interesting observation on your door jamming when jacking up your rig.
I notice from you signature that your rig is about a 31 footer on the E450. This is of course a heavy unit and probably loads the E450's chassis and frame severely, which stands to reason would show up under jacking situations in ways that you describe.
We level our 24 foot Class C a lot when camping using up to five leveling step-blocks to get three-point leveling. For instance, all four rear tires and one front tire up on blocks in rough or tilted drycamping spots. We've never incountered a jamming coach door during any of our leveling operations at a campsite. Perhaps your observation makes my point about the E450 chassis helping to prevent coach structure deformation when the E450 is used under smaller and lighter Class C rigs ... that otherwise could do just fine with the E350 chassis under normal camping situations where surfaces under the motorhome don't tend to twist one end of the motorhome in the opposite direction of the other end of the motorhome.
Expedition RV vehicles deal with the issue using of course both very heavy duty vehicle frames, in conjunction with coach structure mounting schemes that eliminate transfer of frame torque to the coach flooring or it's walls.