I have used that combo in a pretty heavy rain and there was a lot of water in the wheel when I was done. If it was light rain / mist I wouldn't worry but I definitely wouldn't use them in a good rain. Good luck in your race!

One thing I'd suggest is giving the wheels a quick flick while they are still on the transition rack. Or getting going from the mount line is going to be like trying to go up an steep incline from a dead stop.

I learned this tye hard way with HED Jet wheels with heavy rains a couple of times. It took quite a bit of effort to spin all that water out of the fairings and not feel like I was riding on concrete filled wheels. I'll probably forget in the heat of the moment the next time it happens too whenever I get back to racing.