I see it as:
~21.5" C/L of the pivot to C/L of axle slid all the way forward.
~11.25" wide ID between the frame at the pivot point, with some room to play with spacers on the left (this is my least confident measurement as I'm not willing to pop the chain guard off unless requested
...maybe +/- .25").
~10.375" ID between the axle plates.