I called the folks at Timbren today, what they said was interesting.
In no way should I be using the non HD Timbren model, that ALL trucks with a truck camper in them should be using the HD model. He said that the regular model is somewhat taller and will introduce instability to the suspension.
What he did tell me is that there are different stiffness levels available for the HD model. (Nowhere is that information listed on their website).
He recommended that I drop a level in stiffness, then proceeded to give me a string of numbers to add behind the normal model number when ordering.
My normal Model is DRTT3500CA, then I need to add CW (comes with)A0103B-65
So to order that, I now have to go through a Timbren dealer that has a return policy in case I don't like the ride.
Before I go to that length, I have decided to try the upper Stableloads in conjunction with my lower Stableloads and see how things feel.