After letting the truck bedliner cure, it seems that the aerosol type doesn’t have what it takes to cure hard enough to protect the keel. SOOOO… it looks like I’ll go back to the tried and true system of using fiberglass tape (or possibly kevlar felt), and resin thickened with graphite powder and either milled kevlar fibers or another form of filler. The graphite adds lubricity along with some strength, and the other filler will be chosen for impact and abrasion resistance. A good link for the keel strip (or skid strip) repair/reinforcement can be found here: http://www.redrockstore.com/canoerepair/skidplaterebuild/skid_plate_repair.htm
I will, however, keep the samples out in the sun to see if they cure farther than their current tough rubber consistency.