It seems like us humans can be divided into fast coolers, medium coolers, and slow coolers, and depending on who you are can determine what you need to wear... once the water temp is above 65 I most often am wearing a set of IR shorts lined with 3 mil neoprene an IR thickskin/thin skin and a shorty breathable splash top or long sleeve capiliene for the sun. I find having a little neoprene makes unexpected water time better, and it is not so much that you get all whacky from being too hot.
But, dont go for long hikes or bikes wearing neoprene. That ends badly. I know.
As an added bonus the high back keeps away the unfortunate mid back sunburn, and gives a little love to those with older backs...