I am in the process of making Rhino a bin cage. I have 3x 31l tubs, with lot's of floor space, ready to be drilled and stacked. They are quite low, so I was going to get a flying saucer wheel for her. However, looking at it in P@H, it looked TINY!? Even though the ham on the pic was a syrian, I think Rhino would fill it! Has anyone had experiance with this and would the Large size rat version be better for her?