Import geospatial data into existing PDF

Question: Is there a way to export geospatial data from CalTopo and import it into a PDF?

Background: I'm using LaTeX to produce a document that has many embedded hiking trail maps. I use CalTopo to prepare the maps and generate PDFs. I also produce 1 page maps so that they can be individually imported into Avenza. The maps need a legend so I use LaTeX to overlay a legend on the CalTopo generated PDF. The result is beautiful maps with legends, but LaTeX loses the geospatial data.

Possible solutions:

1. Generate a legend in CalTopo which appears to be a current unfulfilled feature request.

2. Export geospatial data from CalTopo and import it into my one page maps that I use with Avenza. It doesn't matter that the full document doesn't have geospatial data. That document need not be imported into Avenza. The Pro account level allows for entering a custom QR code string that leads to the one page PDF maps with geospatial data on my server. Done.

Suggestions?