Superchunk bass traps

I have a question for you guys. My room is on 11' x 15' x 8'. I only have 3 wall - wall corners that I can do floor to ceiling ssc traps. The front wall I can only manage 17" x 12" x 12" traps in each corner but in the 1 corner in the back I have I can do a 24" x 17" x 17". Would that be ok or should they all be the same size?