you faggots couldn't group-engineer an adjustable gloryhole if 6 million lives depended on it. the solution is quite simple: the gloryhole itself is 1 foot off the ground and the wall is set on soft soil. there is a shovel in the room so each patron digs deep enough to where his or her individual dick lines up with the hole. the janitorial staff can put the dirt back in after-- that is why there are 3 of them, to avoid wait times
this "doppel-hollen" or double hole, first described in 1000 Plateaus, promotes fitness and also encourages contemplation of mortality since it's a bit like digging one's own grave. plus, the perpendicularly mirrored act of getting in a hole that allows you to then protrude through a different hole in hopes of being encompassed by a third, human hole is foundational feng shui