Finally... the baseplate is done.
On the one hand, the $400 for the installation for a shop to do it started looking pretty good, but many of the issues had to deal with broken hardware (rusted on), parts not fitting right, and needing additional links and so on.
And I was pretty meticulous in doing the job, including some corrosion control as I found areas in the car with some rust underneath. That all took some time.
But the job is now done.