I don't leave bowls of water for the dogs period. Only if I have them on the chain then I'll leave a bowl of water for them because its the law. Even then, my dogs won't drink any anyway. The only way I can get them to drink water is when I'm feeding them. That's when Ill fill their bowl 3/4 of water plus their food in a medium size bowl. That'll keep them hydrate for 24 hours. So yes I take away their bowl of water during their keep, but when they eat, they had enough water to last them until tomorrow. I know exactly what you're talking about when you mentioned dex. That's one way of bringing in your dog to make weight but let me be the one to tell you that that's also another way for you to lose a match. When you're using dex before the show, you're dog is constantly losing moisture, if he can seal the deal in short order like around 30 minutes or less then it'll be fine. But if he can't then hell be in trouble and will look thinner and thinner as the deal goes longer. By the hour mark, he'll look like a skeleton because he is dehydrated.
I do want as much water in them as long as they're willing to drink it. And in order for them to drink the water I have to add it to their feed. You could give them as much as you want, by the 24 hour mark, all that water in their system will be gone already so you'll get their pit weight every time you weigh them after they're empty.
I do this all through their keep until 24 hrs before the show. You want them to be hydrated during the show so they could last 2-3 hours strong! Throughout your keep you don't take water away from them so why would you do it 1-2 days before the show? It don't make sense.
Every time I put one in a keep, I am not aiming at a short deal, but instead a long deal like around 2-3 hours. So in order for my dog to last that long, he has to work 4-6 hours on his working days and in order for him to work that long, he has to be hydrated.