Yes, you can absolutely experience the entire queue and pre-show! In fact, it's set up so you can easily bypass the ride portion. It sounds really nifty.
Also, there's a test seat outside which may give you at least some idea whether you have a chance of fitting on the ride. The only glitch seems to be that the operators are no longer allowed to push the seats closed on people (some folks complained?), so if it can't close by itself, you might not be able to ride when you get inside, even if you could squeeze into the test seat.
Thanks! That's too bad, I don't mind the TMs closing the device for me. Now, is the device just an OST restraint or is there a seat belt involved (I can barely close those seat belts when I do fit fine!)