Ever look at the back of an Animal Plastics cage?
When I got mine I thought " Gee that doesn't look like it will let enough air in "
But it seems to be fine.
Before on my screen top I have a 5" dome light and I cut out for it about 1/2" larger than the light and that was it for air and again it seems to work fine.

Bp's can't use up that much air so I would guess the only concern would be air movement so it doesn't get stale.