came across this today on flickr, so I dunno if its been brought to your attention or if you are already aware:
http://www.flickr.com/photos/gibcurry/2219667134/
"Sonic Youth set list
8/13/85
This show was at the VFW hall
band line-up:
Sonic Youth
Stickdog
Killdozer (pretty sure)
there was a fourth band... I can't remember who they were. I know the date of the show because the flip side of this set list is the fourth bands set list and they happened to write the date on the list."
Not sure which city this show was, the date isn't in the Chronology, so maybe its misdated or maybe not, somewhere in Iowa (Des Moines, Iowa City) perhaps???
notice Cat in the Hat on the setlist...