@bhs Actually the Psycho I wear the most is a 2mm all over. That's good down to mid 40s, but I believe it's not made any more. It's so flexible I really don't know I'm wearing a wetsuit. The Psycho 2 that I was talking about is a 4/3 I've had for 4 years. Most sets very little water gets in, even after a decent crash. I can do a triple set, 18 passes dropping in each end, in any water temp. I do agree with @jipster43 about getting cold standing around between sets. That's why I have several suits. This sport cost us thousands a year, a few hundred dollars to stay comfortable doesn't seem too much. Whilst on the subject of staying warm, my sets were limited to how long I could put up with the pain of cold hands wearing slalom gloves. I started wearing O'neill 1.5mm neoprene gloves. At first it felt like I couldn't get a decent grip on the handle, the gloves were bunching up and almost pulling off my hands. Many people feel this way about these gloves I believe. After about the third set I began to realise that if I couldn't grip well enough in these gloves it was because I was loading the line too much. After a few more sets I found I was consistently skiing on a much lighter line. When the water warmed up again I was reluctant to go back to slalom gloves. In April I was back skiing in shorts, and rubber gloves. Not a cool look. The best I've ever skied is 4@ -35. With the neoprene gloves on I got 3@ -35 on several occasions so they can't be so bad to ski in when you get used to them.
I'd recommend trying the gloves, maybe you can extend your ski season a month each way.