I use 15qt tubs which are slightly larger but I'm able to fit two of those hides along with one of these for a water bowl...

http://www.sugar-glider-store.com/mi...ding-dish.html

I bought the crock dishes at Pier 1 for $1 ea when they were on sale. You might be able to fit the hides in an "L" configuration with the water bowl in the corner.

With that said most of my guys do ok with one hide or no hide in my rack set up.