Do you think a 1 inch lip is enough for the glass to rest against? 1 inch doesn't leave a lot of area to silicone but its that or overkill with a 2 inch lip (2x4 instead of 2x3) which will cut down on the size of the viewing window. as I mentioned before the height is 30 inches so it will come out to 28 or 26inches respectively, any advice/ideas would be appreciated. 
