MissySki
Angel Diva
It's tricky. San Francisco hasn't officially allowed multi-household "social bubbles", but Alameda County (Oakland, Berkeley... generally where a lot of my people live) allows up to 12 people as long as the groupings are "stable" (you can't be a member of more than one bubble in any three-week period).
Interesting! I know some people locally have been doing these bubbles, but I haven’t ventured to join any yet. I’m not sure if there is super specific guidance here like you mentioned, though it’s possible since I haven’t looked into it for myself yet. Definitely will be open to more for ski season with likeminded people though!