I need to sync up 3 tracks of audio to 1 video track for many many takes. How can I keep everything together AND labeled? As far as I can tell, subclips only work on one track... how do I put them together?
Group them.
Another trick I've used is once all the audio is synced render all your audio to a multichannel wave file and replace your audio with that. This is perhaps safer and easier to deal with than Grouping events
You could put them all the timeline, sync them and save that project. Then open up a fresh instance of Vegas, copy the part you want for a subclip, and past it in the new instance of Vegas. Save that as something relevent. Do that as many times as you need for as many 'sub-clips.'
Then Media Manager allows you to import the .veg files into the database, so you could apply any tags and comments you want to them.
"also, rendering all of that seems extremely time consuming..."
A couple of clicks.
What you get is a single wave file with all your audio in it. Almost impossible to get it out of sync. Of course I don't know if this is remotely what you need or not, I was assuming you were doing a multicam edit.
If that's wrong and in fact you're editing vision with double head audio then the above is quite useless.
What you'd probably want it audio with timecode e.g. BWF. Sadly Vegas will not write this kind of file.