I know, I know, I know

Modern surf suits (steamers - like one piece, tight fitting overalls)are composites. For example one with 3 mm thick neoprene panels around the torso for core warmth and 2 mm neoprene for the legs and arms to facilitate movement is a 3/2 surfsuit.

I use a 3/2 steamer surfsuit for boogie boarding in New Zealand in the summer when the water temperatures gets around 15 - 20 Celsius. Swimming hard in a full steamer in 18+ celsius tends to cook a mere mortal like myself.

In the winter I use a 5/4 steamer wet suit. It works pretty good for 10 - 16 Celsius water temperature, but the thicker neoprene makes it a little less flexible.

Putting a neoprene singlet under the suit can help your thermal protection a bit by increasing the thickness of neoprene around your torso.

But a wet suit out of water becomes smelly and uncomfortable. If you get the thing wet it does tend to become a fridge. Having a wind breaker over helps alot though.

Best to spend more time on your brace strokes and rolls I think.

Cheers Pete