Marie:
I did basically the same thing Bill did except once I filled the holes with epoxy and redrilled new ones, I used a thick piece of white plastic to bed the traveller. Then, to adjust for the cambered slot, I used heavy duty stainless steel washers to build up to the correct height under the piece of plastic. So, for the end bolts, I probably needed four washers but in the center, I needed none. This allows water to drain out between the original depression and the plastic/track since the washers actually are slightly raised from the original decking. This has worked out very well with no problems and an easy way for your mainsheet man to work the main with the self-tacking traveller system.
Bob Rude