I don't tow, but I recently added the Roadmaster Active Suspension because I removed my rear blocks and wanted to be prepared if I ever do need to tow. On the lowest setting, it made a huge improvement when standing on the rear bumper and jumping up and down. It basically preloads the leaf springs, plus gives you extra capacity if and when you need it. Also made the rear feel a touch more planted, vs air bags, Timbrens, or Sumo Springs which apparently all ride like crap when actually in contact. The RAS will also lift the rear between 0.75" - 1.5".
I also just put in Bilstein 5100's in the rear (after installing the RAS) and it made the rear a tad bit better it terms of actual damping. For less than $800 total, I think this combo is a good solid start for most situations. If you tow a lot, you likely won't want to remove the rear blocks completely like I did. The regular 4WD blocks are shorter than the Tremor's and seems to be a more popular option. But I think the RAS and stock Tremor blocks would be a bit ridiculous without lifting the front a bit and getting bigger tires.