Opps, I miss read your post in a bad way (right now it seems, I'm in the middle of some kind of sleep deprivation experment)

I think you are going to be okay as you have sketched out. If you do end up with an air gap, one trick that should help is to poke two holes at each end of the air gap, and inject epoxy into it with a syring. Keep the holes on the upper edge of the airgap if possible to prevent the epoxy from running out, or use tape or somthing to block the holes while the epoxy cures.

This makes air bubbles almost dissapear.

good luck

Myrl