This gig is well advertised with multiple flyers found and a note for the 4th November in BAM Magazine 295 (4th Nov 1988).
A review of a Mike Patton Faith No More is found in BAM Magazine 297 (2nd Dec 1988).
FNM Followers - Steffan Chirazi, Kerrang Issue 215 (26th Nov 1988)

An advert for the gig (at flickr.com

The Sacramento Bee - 4 Nov 1988 (pay-per-view) quotes in a list of concerts for the night "I-Beam in San Francisco for what is being billed as the 'return' of Faith No More."

The review of a "recent" Faith No More gig in BAM Magazine 2nd Dec 1988 by Steffan Chirazi (who wrote the Faith No More biography "The Real Story") mentions introducing the new singer, broken cameras and a bad crowd reaction, all points known from interviews about Patton's first gig.

All evidence points to this November gig being the only pre-Real Thing Patton gig.

Ron Delany photographed the band on the night
JoyZine interview with Jim which includes Ron's photograph of the band

San Francisco Examiner, 4 November 1988, C19
- Gig listing for I-Beam, lists Beatnigs as supporting
San Francisco Chronicle, 4th Novmber 1988 - gig listing with Beatnigs

Michael Franti of the Beatnigs doesn't remember playing with Faith No More. Both flyers refer to Faith No More playing with Beatnigs, however the advert on the day in the gig section of BAM Magazine doesn't mention Beatnigs so it is possible Beatnigs didn't play the night.