Thanks Shadyj - I might well do that, but it really depends on the exact measure. I can slide the unit in and out OK, it's just the vertical height between a horizontal crossbeam and the base of the slot that's the issue. In terms of airflow and control-access, all is fine there (although to be honest, once set up, I do tend to leave well alone after some good roomEQing.
Appreciate you taking the time to respond.
Best,
Marc