I elected not to put Keel Guards on the TC 255. The bows are very sharp where they contact the trailer bunks, and I don't think that the plastic would remain adhered. It is not the difficult to do repairs on gel coat--or even put on sacrifical strips of glass cloth with epoxy/aluminum powder.
We did this yearly with our RIB we used in Alaska, beaching it daily on the rocks to take the dogs ashore. On the RIB, we painted the bottom, thus hid the yearly repair--but on a Tom Cat, one could either use white pigment in the epoxy or stay with the dark color of the aluminum powder--in a single stripe--if one elected to do this. I would think that protection would be necessary only over a short distance. Although the brass strips were protective on the C Dory 22, they were very narrow, and some gouges occured on each side.