I wouldn't risk it. It takes your body a lot more than a couple hours to rehydrate. It's dangerous for pro fighters to dehydrate and rehydrate in 24 hours if its more than 10 pounds. Depending on water weight.
I wasn't advising him either way on what to do, just what I've seen people do and how things work in the Mid-West Amateur scene so he can make his own determination on whats best for him from the information.