...maybe a copper strip?

Not being one to go for the high tide line when I beach, I find that I get much more wear and abrasion at the stern area, from dragging the boat around once I've made my landing, i.e., getting it up above the current tide line and turned around for the launch.

This could work at the bow as well. This is 1/2" oval brass strip which has been filed more narrow to match the keel line at the stern. It's available in 3/8" wide as well, but that may be too thin.

The Wooden Boat shop, when it was open, carried this stuff for about $3/foot, while Alaskan Copper and Brass carries it in 10' lengths for about $6/pound, or less than 1/3 the cost, so shop around.

I carved out enough of the original keel to make this more of an inset then an "on the top" application. Brass screws every 6" or so set into small blobs of epoxy inside to keep things from snagging too badly.

One potential worry is that in shaving part of the keel, I have weakened it, as on the outside I have gone all the way to the plywood. The 1.5" tape applied along the keel as part of the original construction is intact all the way around it, though. The inside is unchanged, and most of the 24" or so length of the strip has thickened epoxy in the keel seem, particularly right at the stern.