humidity should be relatively the same through-out the tub, more holes in the front facing side, but id wait a week first and make sure its not just really high right now, check hot side temps, if its above 90 try getting it to 90 which is a good hot side temp and if your is higher it will help humidity.

Water bowl should always be at the cool end regardless of humidity.

I use 3/8th inch holes, if yours are little tiny ones then try making em 3/8th inch. about one inch from the top of the tub.