I think I replied to Pau Hana's thread and mentioned the Timbrens. I still don't have any trail experience with them, but on the road, towing the trailer with some gear in the back and my campershell, my truck drove great and had maybe an inch of sag.
When you order Timbrens, you have to let them know what your application is, and they will probably want you to measure the distance between the frame rail and the leafspring. Based on that measurement, you will get a spacer that is designed to have the actual timbren about 1" from the leafspring unloaded. After you add weight and the leafsprings start to flex, the timbrens will start to make contact with the leafsprings.
The only problem that I have is that I relocated the axle forward to help with rubbing so the timbrens don't center themselves, but they still work.
You will lose some articulation, but you are removing the bumpstop, and the timbren is taking it's place. I'll try and get some pictures of what it looks like when its flexed.
One last thought: the Timbrens were $195 shipped, and I already had the regular All Pro springs with an AAL to help with weight carrying capacity. An engineered set of springs like Deavers or the new All Pros would be less expensive.