Well if you're being backdoored, the surface area in question already, at least in most non-Coneheadian cases, has an established vertical line. Almost like the body's prime meridian. So in this case you just grab the eastern and western hemispheres of said surface where the backdoor exists and mark your point of entry. And then I might suggest some sort of lubricant. Spit also works if you're in a pinch. Sent from my motorola edge 5G UW (2021) using Tapatalk