Min. transom thickness

[US1Fountain]

Hey guys, what has been the thinnest transom you have seen that had no issues being too thin to keep the input shaft from bottoming out in the coupler? Alpha/Bravo setup. I know Merc specs 2" as a min, but sure that includes a saftey factor. Are we speaking 1/16", 1/8" or more under and still safe?
Thanks

[Offshore Ginger]

I just looked at a boat today and the transom thickness was a hair over 1/8 as far as glass goes and it was set up for a number 3 drive .