Guys, guys... the solution to your stiff springs is simple: swap them out for softer springs. That's what I did on my little trailer.
The factory slipper springs are too stiff especially for what you'll be carrying - there's minimal movement with them. The slipper design has too much friction to flex well. It's a poor design, and I don't know why they use it (it's cheap?).
What you need are some longer, softer springs with a real shackle at one end like a real leaf spring is designed to use.
Start here: http://www.jeepforum.com/forum/f27/m...l#post14563473
Keep going to here:
and keep reading through the next few pages - it should cover it all. If not, send me a PM. This was a totally 100% bolt-on affair (yes, I had to drill some holes...).
I used 26" springs because of some quirks on my 4' black trailer. For the 4' red trailer (or any other trailer really) you should be able to use 28" springs, which being slightly longer and a slightly lower spring rate, should ride even better than my 26" springs. And even the 28" springs combined are rated for over 1000lbs (you'll never get there with your little trailers unless you're really trying). I also gained an inch in trailer height even with moving my axle from below the springs to above the springs.