My sister has been involved for many years with an organization (Wen Do Women's Self Defence) that teaches exactly what you are talking about: physical self-defence techniques that work against larger, heavier aggressors, and also verbal techniques, attitudes, avoidance strategies, etc. She books gigs with various community organizations, schools, corporations, and so on; she did a workshop for my daughter's scout troop, for instance. It is very flexible time-wise; for years my sister supported herself doing a combination of regular part-time work, this, and two other kinds of freelancing.
You would have to go through their training to offer their courses, which may or may not be feasible for you, since Wen-Do is based in Toronto. But I bet you could talk to them for ideas.