Thank You all for your replies! All the suggestions were very helpful. I have read, before, about pouring warm water into the wetsuit. I think we will try the 3mm shorty under the 7mm with the warm water and use a boat jacket on the surface.
We are thinking about doing the New Years Eve dive at Dutch Springs. It is 1 dive. We'll try the combination of the 3 mm and 7mm and see how that works. We'll probably race to the changing room after that dive to get into warm clothes. LOL
Thanks again everyone!
Pouring warm water in helps psychologically, but the actual heat gains are temporary and actually can cause MORE heat loss, if you are in a cold air location, since it opens up the previously-constricted blood vessels at the surface of the skin. You feel warmer while the water is there, but once it's gone, you start losing heat rapidly.
I'm the first to ignore this on cold water dive boats that have a jacuzzi we can pull hot water from, but that's the science nonetheless.
Changing clothes is the best sure-fire remedy.