Sorry Niner would love to help but I haven't got a boat nor a trailer nor a trailer board with lights, come to that I still haven't got a Mokka yet either. Ho Hum back to twiddling my fingers in the corner of the waiting room (and no that isn't a euphemism)
Could you not use a standard board, and then put in LED replacement bulbs? There are some threads on this forum giving details of some of these replacement LED bulbs. (just use search)
Hope this helps.