Yeah that JJ Premium at Wal-Mart, being a 22, takes up about as much space as a proper 22, so forget that*.
That being said, you know some guys here have made midgets out of a 22 (or regular 18 for that matter) by going with short legs and sometimes ditching the triangle and wheels also. You'd need to have more room for the bigger bowl, but you'd then save other space by being able to pack more supplies inside of it.
You have options!
* Did you catch my flawed logic above? You could also turn a JJ Premium into a portable the same way the full size 22 or 18 is done, and you'd save a little space compared to them.