Hello Barry,
Just to quickly answer your question and as everyone has already said maybe just a 3 mm would do fine for the depth, but I usually don’t use a wetsuit around this time of the year, and if anything I just use a thermo guard whgich is a .5mm wetsuit top. Anyways the water here in FTL has been as I would say "Perfect for diving" so far with the exception of last week (the water was really choppy, Vis was maybe 10 ft or so). Either way in the end it is your call as to wether to bring a wetsuit or not. Enjoy the dive