Remember that shocks don't do much for load, that's why they're called shock absorbers. What you need for additional load is beefier torsion bars. That's what supports the weight of the vehicle, the shocks just keep it from bouncing all over the place. Stiffer shocks just don't let it happen as much. Coilovers would be a good addition to beefier springs, but our stock mounting position doesn't offer enough clearance.