The rear wall of my listening room has a pocket door over my right shoulder and in the corner. Its normally open for easy access to the laundry room and bathroom. That is all there is on that level.
I don't think it affects the bass as much as it does the L/R balance.
That's another vote for the door. And as already stated get a good solid door with good hardware, otherwise you could create a buzzing monster at some freqs.
Regards,
barts