My Pleasure.
One thing I didn't mention is the mass of load you carry relative to the vans capacity.
Do you think you get close to the vans max axel load.
There are people on this forum, who have fitted the van out; loaded it up; put a roof rack on; then towed a heavy boat (or similar); then all of a sudden have a saggy bottom; without realising they are over-loaded on the rear axel.
If the above rings any bells; you may need to tread more carefully.
If however, when the van is on its maximum duties, you don't suffer from a saggy behind, you'll be fine.