CLICK HERE for the 06 F53 chassis specs. I've been trying to figure this one out off and on for a while. The problem is I don't know how much the house weights and I'm too lazy to completely unload and then reload weighting all the stuff in the coach. Last page of the PDF has the frame to ground heights and frame to axle heights of the chassis WITHOUT the house. Also included is the leaf spring deflection rates in pounds per inch of deflection.
I'm guessing without be able to actual measure the height before the build out starts I'm not sure what my starting point might be with the added question of how much strength have the leafs lost with time.