Maayybe. I was experimenting with getting on the ride vehicle if I didn't have the ability to move my ankle or toes when I was last there. I might have been able to do it if I tried a few more times, but each time when I thought I had it a CM asked me to move and I did need to move my ankle to get into the proper position. For reference, I'm 5'10" with a shoe size of 11 and ~170lbs.
That being said, I tried without a walking boot. They typically add a good amount of girth to the lower leg so I'm skeptical as to whether one larger than me could ride with a boot. If you have a patient CM, you might be able to finagle a way into a position that works, but I'd try out the test seat (assuming you're going after opening day).