It will help a lot to know where you intend to do the teaching. Then, contact the fire department for that area and see if you can get a standing 'open flame' permit for that area, and ask what you would need to do to have it unattended (that way you don't need the marshal there for every class).

www.specialtyinsuranceagency.com/p...ml

The bay area is really big and different.
San Fran requires a FM inspection and lots of permitting stuff I've never dealt with.
Oakland's pretty permit-accessable. You can also (dare I say it) get away with renegade fire in most of oakland (as in, not lake merrit or anywhere where you are likely to incenerate the hills).
Berkeley is no-go. You can try, tell me how it goes. The people's republic of berkeley isn't too big on personal freedoms.
Albany is amazingly cool about this. If you talk with the FM (who actually takes meetings) you can get permission to burn on the albany bulb beach (near the racetrack), for free if you are nice and safe and play nice.
South bay is a mystery to me.

But perhaps I'm not an independant observer, since I live in the east bay, and have a mild grudge against berkeley hipocracy.