At AMBICO currently, a labourer in their factory spends a significant amount of time measuring and marking the placement of the cutout plate to install flush bolts in the side of doors. Flush bolts are used to secure the inactive door of a pair of doors, extending into the frame head and can also extend into a floor strike (floor strike is a component of a door hardware system that is installed in the floor to receive and secure a bolt or latch from the bottom of a door). In this application, the active door would typically have a lockset which latches into a strike mounted on the edge of the inactive door. A flush bolt will be operational within the door skins. 
The current jig (first picture) is placed by hand and held in place while using a handheld router to cut the slot. The placement of this cutout must be in a very precise location and changes depending on the thickness of the door. The company currently uses many thicknesses of doors between 1-3/4in to 2-3/4in.

Your task is to design a reusable jig that can be used to route out the cutout for the flush bolts to speed up the time required for this process and increase precision of the manufacturing process. It should be fastened, clamped or placed on the routering jig for example (without damaging the door) while they work so they don't have to hold it in place. The jig must be extremely precise and durable while being universal for different doors. It should be quick to install and easy to use for the labourer. Simple and compact is key.