Using tips gleaned from the following two tickets, I was able to get my HA setup running:
https://github.com/rancher/rancher/issues/4697
https://github.com/rancher/rancher/issues/4634
The Rancher HA architecture involves quite a few moving pieces, so I understand the potential complexity. I’m sure a smoother path to success will emerge over time. In the meantime, my team can now get down to the real work of setting up are services and applications.