Oh no the wheel would fit just fine! I personally think so at least. There are three doors. One closer to the bottom, one closer to the top and a big one right on top. I think the first one looks fuller but my rats love their's and so do I.

If you really nated to spend the money on Ferret Nations I heard they were great but they are very expensive IMO. There may possibly be a Rat Nation if the company decides to go forward with the idea.