I've used some Energy Suspension parts in the past with good luck. Prior to buying lower StableLoad wedges, I used blocks of pressure treated wood held in place by a lag bolt through the spring. My truck needed the full wedge height help since it was carrying a camper twice your pin weight, yet I knew how poorly it rode unloaded with the lower spring engaged - This confirmed that I needed an easy way to engage or disengage the wedge between the springs. I felt better after my testing in buying the StableLoads verses just hoping they would have the desired affect.
If you have trouble getting StableLoads between the spring pack, you can select 1-3 plates for varying thickness. When putting the bolt in I also had to jack up the receiver to take weight off the springs (I realized I could have added air to my bags to do the same later). Some people have to trim a little length off the mounting bolt or use a pry bar to get that little extra gap on install.