Can you convert Latex to Word (or ODT, etc.), perhaps with Pandoc, and then from that to epub (e.g. Google Docs allows you to download a Doc as an epub)?
Yes, in theory.. but in practice it didn't work when I tried that route. Because I use the Tufte-Book template, there is a constant margin to the side of the main content that holds figures, equations, and such.
This margin gets brutalized by every program (even the propriety ones Amazon built).
Lessons learned. I need to be more mindful of the various conversion processes in the future.
My conclusion with a self-published book a number of years ago was that, once you get beyond flowing text, creating a Kindle version gets a lot harder. It can clearly be done--e.g. there are Kindle format guidebooks that work well. But when I did another self-published book a few years later, I was giving it away anyway so I just did a PDF version for tablets. (My last one is through a publisher but it's also mostly text.)
I've often been disappointed at the type of html it's possible to force out of (La)TeX. And epubs are pretty much html, css and images.
I generally think that some kind of markdown with the help of pandoc is the happy path for pleasant writing/editing and good output for html/epub and print/pdf.
I did find this, that have some hints on how to get xml, and then xhtml with support for equations - but it looks cumbersome:
You know, the book looks interesting - but not in pdf, and not as a physical book (I try to live without physical books - won't I be a sad case when the singularity pushes us into post-apocalypse?)
Did you cconsider selling access to the source (eg: private github repo, suitable license)?
Not sure I get the reference. Apparently it's easy to end up in a position like the author, with a large (La)TeX manuscript that easily produce good pdf/PS, but mediocre to awful html/epub.
One option for getting help would be to open up everything to everyone - selling access to the source might be a way to retain some income while enlisting some help in conversion from volunteers (yes, we would first pay full price for the content, then volunteer to try conversion options to produce passable epub output).
Book looks interesting, btw!