ICYG Update
The first 100 times I'd checked out Oddsock's Stream Transcoder, I don't think I fully appreciated what it did. Turns out, it's the perfect tool to solve this problem. After a quick configuration, I fired it up and it's taking a "master ICYG" Vorbis Q10 stream, transcoding it down to ICYG's normal Quality 0, and directing it to the public ICYG mountpoint. Too cool. Thanks to Oddsock for the tool.
Update (11/12 8:20a): ST wet the bed overnight and was running in a non-working state when I went to check it. It wasn't sending output to the Icecast server at all. I killed it, cranked the master ICYG stream down to Q8, and restarted ST.
Update (11/13 8:27a): ST stopped working again. I'm removing it from the mix for now. I'll have to look for some testimonials to see how others are using it. Perhaps the Unix version is better? I don't want to compromise the quality of the public Q0 stream by two recompression cycles that are too harsh.