Jacksonville Wetsuit Question

[Rldevogt]

I have a spearfishing fishing trip coming up in November out of the Jacksonville area. I shouldn't be going deeper than 100 feet. I normally dive the North Florida springs in a shirt and some board shorts for approximately 45 minutes before getting cold. I have a 5mil wetsuit and when I dive it in the springs it is way too hot and I get uncomfortable very fast. What size wetsuit would be best? I can get a MAKO 2 mill reversible wetsuit with hood for about 200 or I can pick up a 1.5 mil rash guard for a lot less. I am hoping to make this spear fishing at least every other month.
Any input would be greatly appreciated
Thanks in advance.
-Ray-

 

[100days-a-year]

Water in 100' will be around 70s.Likely to be 80 degree daytime temps on the boat.I dive 2 to 3 mm almost year round now but I dive further out.