Consider attending the Squat and Deadlift Camp that Diego and Emily Socolinsky are hosting next weekend. That may be a more accessible option for you right now.
Thanks all for the responses. I sat down with one of the clubs and they explained that their obstacle is not my lack of insurance specifically but my lack of certification: if someone is injured, the club rather than me will be the target of any lawsuit because they have the deeper pockets and so are the obvious target to sue. They need a certification on paper to deflect charges made against their own liability. There is, however a certified S&C coach there (although the amount of strength training he actually runs is minimal) who said I may be able to provide coaching under his supervision. The impression I got is that he's seen a lot of dangerous things done in the weight room (I didn't pry as to what) and would need to satisfy himself that I wasn't doing anything of that kind.
All the coaching experience I have gained so far has been with people largely or totally unfamiliar with barbell training, and that's how I intend to continue insofar as I can, with or without a certification. The clubs I'm talking to have access to decently-equipped weight training facilities but I know for a fact they don't use them for anything resembling serious barbell training (for a number of reasons).
I'll certainly attend the next SS camps I can get to, but in the long-run I think I'm best off acquiring some sort of interim certification, as Nick suggested, which I can treat as a tool to help me achieve the SSC certification.