Guidance on replacing trailer keel rollers with a keel board

[Chessie]

I plan to install a keel board, since my trailer has only 3 rollers, and the keel rests on only 2 with the boat drawn up to the bow roller stop. Can't be good for the fiberglass.

I really wanted to build a roller bunk, perhaps out of galvanized steel L brackets with keel rollers every 8" or so, but I'm daunted by that project in terms of cost and how to modify the trailer's existing roller mounting points.
 
Does anyone have photos of their keel board install? I spoke with Hutchins several years ago, and they said they stopped putting rollers on all the CP16 trailers and just put in keel boards instead. Photos of mounting points, board dimensions, and keel pad/cover material would be helpful