I dive wet into the colder part of the year. SI are only an issue because of evaporation from the wetsuit. No evaporation = no cooling and it is back to being thermal protection. Locally I have a lined boat coat. Put it on over the 7mm and the 7mm is back to keeping me warm. When I am traveling I bring a set of foul weather rain gear, extra large size. During the SI I put the rain gear on over the wet suit. No wind, no evaporation.
Makes a big difference.
Makes a big difference.