Instead of a z-drag for your trailer, or rollers, or astroturf, or 303--just repack your trailer bearings with submersible grease and replace your trailer tail lights with submersible LED's. I got a kit at checkers for around $60. Rewiring your trailer will take time (and so will repacking your bearings annually), but when you float your boat halfway onto the trailer, and slide it the rest of the way (by yourself), you'll know it was time well spent. My 14' self-bailer slides off the trailer and back on (rigged for an overnight) with one person. My trailer is a flatbed with a painted plywood deck. Good luck.