There are lots of ideas here.
This is what I do. It is simply 4 "bump stop rubbers" from the earth moving supply outlet. They have a 3/8" stud and nut already fitted. I simply lift the pickup to full suspension travel and slip them into the holes at the front and rear of both helper springs. When not required I simply take them out.
Oh yeah... and they are quiet!!!

Yes, as you can see I have lowered my truck 6 inches, so this was a necessity for me, our Summerwind is 2760# empty. I have a small set of air bags but don't really need them. They mainly get used getting in and out of steep entries and for hitching up the trailer.