I have a similar constant weight in my Pathfinder. I blew out the whole rear suspension including bending the panhard bar. I just replaced everything. I went with NRC9448 coil springs and Bilstein 5100 shocks. Even with all the weight it's sitting at about a 4" lift. I think it will settle to about 3". I would recommend my setup only if you plan on lifting the front too. Otherwise I think NRC9447 would be better for you with the 5100s.