Here's my Pentair tank. The base dimensions are 6x3ft. So far I have had it up and running for about two months with no issues so far. Current stock is a pair of orbignyi, two florida gar and a marble motoro.
They weren't trying to bite the rays but when food hit the bottom theyed drag their snout all over the sand whatever they hit they would bite. Almost everyday they would accidentally bite the rays. Nothing major usually they would just bite their disc and let go immediately. The final straw was when my 17in Florida gar got drug around the tank while hanging on to my marbles tail.
I like it. Nice setup.
Just be prepared to clean the gunk out from under the tiles every now and then. But Im sure you knew that.
Wish I had the space for some of these tubs. looks good.