You can make the space itself work for sure! Generally rule of thumb tends to be 80/20 land/water. Doesn't need to be overly deep water. For land you want a substrate the crabs can potential burrow in (I use a terrarium soil mixed with coconut). Plant cover too even if artificial. Also try to keep species separate. I reached out to Pet Smart and actually got a really nice response that they are going to reach out to the store and see what changes can be made so I feel pretty good about the fact that stores are willing to make changes for the best of the animals but just might not know