Well, I went ahead and made up a new light box. I'll be using ten 50PAR20's, mini flood halogens. Pics show 50 watt regular type bulbs which will be swapped out today for the proper bulbs.
I'm punching out rubber gaskets to put over the bulbs just below the threads to try to keep the sand out of the sockets. A s/s sleeve will press the rubber up tight to the socket hopefully locking everything out.