Have not used gatorback, but have been very happy with this product from BassPro Shops: http://www.basspro.com/Tie-Down-Self-Centering-Bunks-GlideOn-Covers/product/52357/#desc-tab
The picture of this product is somewhat deceiving. What you get is (4) pieces of staple-shaped plastic covers that attach with stainless screws to the edges of the 2X4 bunks (not the top of the boards). Each piece is 4 ft. long. Each piece has a squared-off end and a rounded-off molded end to protect the 2x4 bunk when you drive on or off. The glide-ons have molded-in grooves that really do force the boat towards the center. In my case, I had 9 ft. rotted boards that I replaced with new treated boards. Then I attached two 4 ft. glide-ons to each board which left a 1 ft. space in the middle. I covered the one ft. space with standard bunk carpet. Been using the glide-ons about 5 years with no issues - one of the best things I've done to help trailering my 16 ft. aluminum Bass Tracker.