I'm looking to add a layer of warmth to my core. I have a 3 mm wetsuit, but lately I've been getting cold. I wear a 2-piece bathing suit, then a lycra skin for ease of don and doff of the wetsuit, so I don't want to add too much bulk. I'm also busty up top. I like the idea of the quick dry merino layer or similar material. Lavacore Polytherm and Sharkskin seem to have some good products. Any recommendations which you prefer or have used? Other brand recommendations would be helpful also.