Hmm, I suppose it might be possible to stream the epub to memory - but while it might pull in some nicer formatting, I think it'd also cause other problems because I'd still have to pull from the site to get stats stuff and to add the kudos functionality (and eventually I'd like to add bookmark and comment functionality, but those are more complex interactions)
Anyway! I did in fact get a release up - links and notes are in this journal post:
https://momijizukamori.dreamwidth.org/482636.html