I forsee one other small problem, though your idea is original and cool. White's aren't very good swimmers, but so long as the water isn't too deep I don't see a problem besides the crickets. It would just be a shame if one of your heavy White's miss-jumped or stepped or fell off of a plant, landed in the water and was unable to get back out. That would be my greatest fear when setting up a water based viv for White's. But other than that, as long as you're not planning on making the water too deep, I say go for it. It sounds like a cool idea.