Quite simple, either go for kokatat or palm, they're the best out there, .. I've used both kokatat and the palm sidewinder and too be honest they're pretty similar, but again kokatat is expensive, sorry but i don't know the names of the different kokatat models, i only know them to see.
like joey said don't wear a wetsuit underneath, it's too restrictive, and if you buy a good cag all you need is one or two thermals underneath ( god's are selling the palm thermal top for 35euro, which is a sweet deal, i bought one and that thermal alone is enough, under a dry cag you'll be sweating)
Buy wet suit trousers, and wear some fleece trousers underneath, still warm when you swim, and anyways now that you've your own boat you won't be swimming for long!