I can't for the life of me figure out how to do the back arms with how my 5er is laid out, but just having the front done was a pretty impressive gain in stability.
I had the Steadyfast system on my trailer and was going to buy them for the fiver. Keystone offered a promotional package that included JT's on the front only. I purchased one arm from Steadyfast for the back legs. That is mounted on the frame and runs to the opposited pad in the rear. My rear legs are right behind the tires and there was no cross beam to mount the JT's like there is in front. I can really tell when I get in a hurry and forget to tighten down the screws with the trailer motion. Once they are locked down the trailer is rock solid.