I'm not sure what your dimensions are in, (mm I think) I came up with 13' x 17' that's definitely doable. I've seen them in rooms smaller than that. What kind of setup are you looking at?
There should be some pictures of some that size in the galleries. I'm not sure how many people call out the dimensions of their rooms though.
Mine is currently in a room that has a slight "L" shape to it. Its 21-22' long, the first 10-11' its 12' wide and then it widens to 14' for the other 10-11'. My screen is on the narrow end of the room. I fit a 120" 2.35:1 screen in there, barely
Most of the seating is in the wider 14' end of the room.
If I could build one from scratch or add on to my house I would like an interior dimension of 18' x 25' with a 9' ceiling.