Understood. Is your project open source? I'm curious to see what the solution looks like when you sort it out. I feel like there must be a lot of heavy lifting

Understood. Is your project open source? I'm curious to see what the solution looks like when you sort it out. I feel like there must be a lot of heavy lifting (but also a lot of cruft if all you care about is a narrow case) being done by pdflatex to get to an output pdf. It will be interesting to see what the minimal solution looks like.