@Island, thank you for this post.
Until now I had thought of northern north America as a godless walking destination. I knew about the Pacific Coastal Trail and the Appalachian Trail from reading about Joe Valesko when purchasing his zPacks light-weight tramping products (he had also walked Te Araroa, which got me more interested).
From a week long stay in SanFran in August 2008 I was aware of the mission church there and of the parish church alongside. But was not aware of the extensive set of mission churches extedning from Mexico to well north of Oakland.
I keep everything on my tablet (because of its 10" screen). And my go to map apps are all Open Street Maps (OSM) based. My approach is this: if the route is not marked in OSM, it does not exist (!!??)
I begun looking at the route using the links you have given above, especially the interactive link. And have downloaded the GPX files.
While not explicitly stated, these files seem to be available for not for profit use.
To help me keep a focus on this camino I am forming an intention to map the route in OSM using the GPX files. (For the simplest of reasons: southern California is (was?) quicker and cheaper to get to than northern Europe.)
Can you please offer any observations on this intention to map the route.
Kia kaha, kia maia, kia manawanui (Be strong, confident and patient - QEII, 6 April 2020)