The measured height of the black plastic mount for the mini is 11.84mm along the trough that holds the fiber, and 13.24mm at the very ends of the trough. The CAD file shows 13mm for the ends of the trough and 12mm for the sides of the trough: http://download.lulzbot.com/Mini/1.0/production_parts/freecad/wiper_mount_v1.0.fcstd
The bed corner is made of flexible filament, and is 4mm thick, but probably gets compressed a little. There is a little nub directly under the glass that is 0.99mm high on 3 mm base: http://download.lulzbot.com/Mini/1.0/production_parts/freecad/bed_corner_v2.2.fcstd
Both the wiper trough and bed corners sit flush on the same aluminum plate.
So the difference between the bottom of the glass plate and the top of the wiper trough is probably between 7.5 and 8mm. I’m printing right now so can’t measure the glass/PEI sheet, but I’d suspect that whatever you have on hand would be close enough – subtract that from this figure and you should be good to go.