no,, like mentioned, the shock mounts are not designed to support load, second, you should look for a stiffer spring rate. to be honest, most mass produced manufacturers offer only one spring rate for a particular spring so your kinda SOL, you can install a spacer in the front to level it out if thats a concern.
yes you could put in air bumps, but now your talking a considerable investment for something that might be able to solve for pennys on the dollar.