I don't know how to add books if I can't find them anywhere :( Just creating a post, then.
El Presidio Rides North
In a post-zombie apocalypse world, an almost-madman named Mercury and his newfound companion, Gaga, seek refuge in a RV-turned-mobile-fortress.Status:
Also available on AO2: http://archiveofourown.org/works/798554
Published October 23rd 2011 by Shousetsu Bang*Bang
Complete with the soundtrack.