To start, I removed the carpeted liner from the trunk lid. To do that was fairly easy, I just had to pop out the little plastic snaps, pop off the latch cover (already off in this picture), and take off the plastic handle (to the left, not yet removed):
To drill the holes for the mount, I started by using a factory hole in this "tunnel" that was centered on the vehicle from side to side. I chose a drill bit that fit this hole perfectly, that would reach the whole way through to the top of the trunk lid. I then used this to drill my pilot hole. Below you can see me lining up my drill from the inside, and the resulting pilot hole as seen on the top of the trunk lid. The picture of the top of the trunk lid is a little confusing to look at, because you can see the unfinished drywall of my garage ceiling reflected on the closed trunk...sorry for that!
At this point I have 2 primary things to do, in order to have somewhat decent HF capability in the car. The first is to install bonding straps between the various sheetmetal parts of the car. Some of the hardware I need for that I ordered from Amazon today, so that will probably be a project next week sometime. Once the bonding is done, I can do final tuning on the antennas. At that point I'll have working HF......but I'll be far from done with this project. Check back soon to see what's coming!