I was wrong about everything! (Suspension problems, part 2)

OP is trying to use a retrofitted van, that didn't have the "rv prep package," but he's in a similar situation to many Class C owners, like me, who end up running "right at" GVWR. Some have the luxury of a ton or more of NCC, but not everybody. RVing takes on a triple threat:
1. Get it to do what we need it to do
2. Have it drive, handle, and stop reasonably well
3. Have a reasonable degree of durability
Not easy.