You need if you really want to get into Glory hole action a portable premade one with a carry case, or get a portable drill with a hole saw attachment.
You only need a small peep hole or one large enough to stick a finger through to signal what you want.
Back in the 60's you had to use a manual hand drill and then file like crazy. Growing up in the rural south glory holes were everywhere and very active at least in rural North Florida and Southern Alabama. This was before computers or cell phones and the closet Gay bar was 3 hours away and it also was before you had to worry about catching anything antibiotics wouldn't get rid of. I did glory hole action a lot back then, never did do the under the stall thing. I know it is not considered PC anymore to like glory hole action but I sure loved it but it might have been because that is all there was.
new methods
old method