I believe the Socorro Aggressor leaves from San Jose del Cabo rather than Cabo San Lucas. Will you be staying in Cabo San Lucas and then transferring to your boat?
I went to the Revillagigedos last May. I did some fun local diving out of Cabo San Lucas before my liveaboard, which left from there. The water temps during my trip were 72-74, mostly 73. I wore a full 7 mm and a 5/3 hooded vest. I was one of the few divers who stayed warm on all the dives. Of course, exposure protection and warmth are personal.