Yes, it can actually fit a pack and play. I managed to get it in there by unfolding and locking it in place within the bathroom. I believe it won't fit through the door otherwise. It absolutely takes up all the room and makes the restroom pretty much unusable for anything else.
The disadvantage to using that bathroom is that it has a frosted glass door with a wood frame. (Whose brilliant idea was putting a glass door on a guest bathroom?!) Sound and light travel right through it. The better option is the laundry room off the living room. It's enormous, blocks out most light, and is much more sound proof. However, it limits your clothes washing abilities and if you're like my wife, that is essential.
The master bath also has plenty of room for it. Hope that helps.