Jims idea is a good one. Remember your drilling into a cored deck
and if the bedding breaks down over time(it always does) you will get some water
inside your deck core
.. Make sure the holes you drill are properly sealed at the edges so any water
leaking can not get into the core
. I drill an over sized hole through the top layer of glass and then use a bent nail in a drill to remove the deck core, fill it up with epoxy
and the next day I drill the new smaller hole in the centre and bed
the fitting. If this should leak on day the water will go through the deck but never into it.