Hello Zack,
Sorry for being bit out of touch as I'm traveling and my access to Internet is sporadic.
I'm still working on Stegonotorus. I developed the webpage_tester (now on f--webpage-tester branch on github), that is curl using Stegotorus to download anything on the web and compare it with the original. It is based on assumption that is my best approximation for a browser. I did that in a hope to catch the bug, but I haven't. Basically I failed to browse anything unreliably. I can download 20 megabytes or so with no error. It takes a long time, but It doesn't fail.
My payload server is the apache payload server but that shouldn't make a huge difference. I think my payloads even have smaller capacity and less efficient than your fake ones.
Anyway, I'm going to tweak the tester proxy to drops packets at random, to force the ack into play, I'll get back to you with more update.
Cheers, vmon