I may be a bit late to this, but an airbag doesn't only have to work while unloaded.
The Kelderman setup may work like that, due to not having a heavy enough bag or whatever. You would actually think the Kelderman setup would reduce load on the bag by using the leaf spring as a lever and the front eye as the pivot. Any thoughts on ditching the leaf and making a solid bar of some sort that would allow a semi-style bag's height and still bolt up to the front eye and axle using stock hardware?
Doing some math on our trucks at work:
There's 5 axles, and we can gross 88k. the front axle usually ends up at around 10-12k if I think right, so that leaves 76k between the airbags. According to my windows calculator that's 19k per axle left over. Our semi suspensions use a single leaf that's bent over the axle and drops down behind it to allow the airbag's height to fit below the frame. They should be able to support the weight of a 1stgen easily even at a lower air pressure,
if there's room to get them mounted somewhere under there and you want to waste/burn the time/skills/materials/money to do it.
After thinking about this some today, I'm not sure the leaf spring will act as a lever after all. Considering the pivot itself is mounted to the very load it's trying to lift...
