If you read Alan's response, that explains why you don't want to place a sub in an enclosed area. Lowwwww frequencies, say 80hz and below, are omnidirectional. They radiate in all directions not just forwards. Also, the sub is affected by room characteristics, room size, furnishings, etc. Placing it in an enclosed area will defeat the purpose of having a sub.
Can it be done, yes. Is it wise, no.
I still don't see with that size of room, why you can't find some location along a wall, behind a chair, etc. to place the sub. It does not have that big of a footprint.
