Correct, they only extend to 26-1/2 ish, and the rrds for 3.5” lift extend 29.3 “Meaning the Mopar shocks aren't long enough, right? Limiting down travel? I was read that they kind of do that with the mopar springs so that doesn't surprise me. I would eventually probably get their RRDs too, but just not yet. Did the ride height change any from the mopar to the RK? So if my memory serves me correct, I think the RK spring rate is a little higher than the mopar springs. Adding a mopar steel bumper and winch made my front drop about 1/2. was looking to level that out with different springs because I don't want to add spacers. Similarly, I bought a travel trailer and was looking for stiffer springs in the rear for that.
In my case, I got almost 3.5” of lift with my Mopar lift so by the time I switched to rk they only settled a 1/2”. So I only actually gained a 1/2” in ride height.
If you’re going with the 2.5 “ lift the rrds for that lift will extend an inch less, at 28.3”. Still gaining a couple inches of travel. As far as sag from the weight in front, I use 1/2” spacers in the front of mine to get it to sit like I want it.
I think the rk springs would carry the weight better. You’ll have to compare spring rates though to be sure.