...I have a similar set up but with a shell and haul a lot of tools with my Ranger...
...Gabriel makes a coilover for loads to replace your rear shocks at about $79 a pair which I ran for a while...I also off road my truck and found the coilovers a little to stiff so I wound up going with AAL's (add a leafs) added to the stock springs...
...After a couple years of hauling tools all week and offroading pretty regular, my AAL's and leafs have flattened, but for 2 years, this has been the perfect setup for me...
...I plan on doing a mixture of another used good set of Ranger springs, Explorer springs, and AAL's to test them out...