Originally Posted by Scott Whigham
I've read that it's best to have an air gap with a 4" or 6" deep cloud - say 4" air gap, for example - but you're saying that your room is less than eight feet high. I'd assume you can't add in both a 4" or 6" deep trap along with a 4" or 6" air gap - you'll just make the room unlivable at that point. So I'd assume you just try to mount it 1" or so off the ceiling.
Even a 4" trap with 4" gap still leaves over 7' overall height, unless you're really tall it shouldn't be an issue.
A gap is beneficial but not essential, it will still work without one just maybe not quite as well. Most people's home studios are a trade off between functionality & space but they get a workable sound from their rooms.
If you put it flush to the ceiling & can't tell a difference then move it down until you can or where you can't bear it to be any lower, it will cost some time but not much else