Yup ... I got it to work. Well, good enough. And what I couldn't get to work I am not sure was a shortcoming of Calibre or my ability to configure it. I think it was my ability to create a folder on my device. From windows explorer I could create a folder, but not rename it. Seemed like a permissions thing. And I'm pretty sure Calibre was choking on being able to create a folder for the same reason.
So I ditched trying to separate my comics from my books. Turns out, my two readers deal with mutually exclusive formats. So I won't see mobis in my comic reader or cbr/zs in the kindle app.
I took almost exactly the format out of the example in this link:
https://manual.calibre-ebook.com/tem...send-templates
Attached is my adaptation. I just added the zero-padding that I liked from the previous format.
I had been trying to use the lower portion to send CBR and CBZ to a /Comics folder, and MOBI and PDF to a /Books folder. I actually believe that would probably work, and in which case would be
exactly what I was looking for. Except my tablet was misbehaving and I'm calling "done is good."
Thanks everyone for the help!