Your trailer is basically a float on type with rollers instead of skid plates. Most of the guys around here with float-on types just dunk the trailer and drive on, and Capt. Chuck's set-up should work unless they don't allow power loading in your area, in which case you'll need the rollers. If that's the case, I see 2 possible options: 1. (Big bucks) Cut a couple of feet off the aft end of the bunks and install the EZ Loader self-centering setup of 16 rollers on rear cross member. 2. (~$25) Replace whichever roller it's jumping off of with one of these:
www.westmarine.com