[niles]

After much thought about this touchy problem, I settled on a variant of the other posters.
You will need to, be able to easily remove to get to MC, hoses, leaks, etc. I bonded a 1 1/4 strip of 1/4 in wood on the top and bottom of the glass opening. I mount the vents to the wood with a no 6/8 sheet metal screw that will stay on a magnetic phillips head screw driver. This will allow one person to screw them in/out after you get the holes drilled in the right place
gn