I got some graphite and added to the epoxy I used for the last couple of coats on the centerboard.
It was not particularly messy. Here is the best deal (including shipping) I found for graphite:
https://www.amazon.com/gp/product/B07VKPXC3D/(Like in the manual, I did not paint the centerboard).
After one season the water, I have no idea what the bottom of my keel or the centerboard look like. I'd need
to jump in the water with a face mask to find out...
You could also put a strip of slippery teflon-like material over the carpet on the bottom of the trough.
And be sure to put a couple of extra layers of fiberglass on the bottom of the keel, especially around the front corner!
A potential source of damage is accidentally trying to pull the boat onto the trailer when the keel is not properly centered in the trough.
If the rear of your trailer has any nasty sharp edges or projections, you might want to put something over them.
Doug