over in ocean springs I wear a 3/2 farmer john... w/5mm booties
under that i wear the booty foot liner things, and I cut some polypro long john pants to knee length.. and a polypro shirt under a spray top.
the poly pro is great base layer stuff... it's cheap, get some at a mil surplus store.
the polypro i wear under shorts in fall... and the polypro top i wear under my lifejacket in fall... the top however I cut the sleeves out off... kinda redneck, but that's how we roll.
you could get a sunny day in the high 60s. go to Juanas. they're cool and you can leave the boat on the beach overnight...