If you're still getting wet under your wetsuit, then you need a new wetsuit. Try a Rip Curl elastomax. It's "wet" in name only. If I get totally dunked, sometimes a tiny bit of water will trickle down the neck opening. But nothing ever enters through the ankles or the wrists. And the comfort level and flexibility is way better than a drysuit.

I have a bit of another approach than must guys here:

I am combining wetsuits. I am using a 3mm wetsuit and when it gets really cold I am wearing a 2mm shorty below. That suits me fine and is very cheap, as a 3mm and a shorty is something I need in any event... and even if some water is coming in, it's not cooling me down drastically as the shorty inside is an additional barrier.

I think I am generally a person who feels constantly cold, but with this combination I can kite until the lake starts to freeze.

One thing to add: I think something that helps a lot for keeping me warm is the Dakine protection harness that I am using.

My biggest problem are the feet, the hands and the time on the beach after I stopped kiting.