Hello,
Please read carefully about what i'd like to offer. (right, i'm not a bot ;)). What would You say about using pure nginx (or combination of nginx + varnish) to accomplish your project? I'd like to know a bit more about this project so i could take a look again at your problem with more details in mind, but i think we can setup pretty good proxy on already battle hardened and tested, really good piece of software. Please let me know if You're interested with more details ;-)
Kind regards,
Chris.