I use a camera tripod to hold a torpedo laser level in position and use the laser line to locate the plane. Set the laser to a plane rather than a line, and use the level to set the position. Be sure to get it located in both planes. In the example shown in the photo, it needed to be located both vertically (in pitch) and in yaw.
You can mark the part to match, or press tape in position to identify the location. The most time-consuming part of this was adjusting the torpedo level.
My tripod has a crossbar, which I find very handy. But the concept holds even if yours doesn’t, and you are shooting the laser from the side. Mark something identifiable from the far side and and move the tripod to that side and realign it.
