Yesterday I installed the pickguard and stuck some tape to it, to trace the route needed to accomodate the goldfoil pickup.
Then I cut out the opening with a fine blade on the jigsaw. I find this is not the most precise way to do this, but don't know how to do it otherwise... Ideas are welcome as I guess I will encounter this more often.
From a distance, the result looks good enough for me.
Then I routed out the neck pickup cavity. With a long 8mm drill, the hole for the wire was drilled.
Put together again, this is the current state of the build!