Yeah, I don’t like the term mastermind, either, but it’s a name for groups like this which I’ve used in the past, elsewhere. Keeping it as a nominal working group may make the most sense, given the points you outline.
A few of the regulars can’t make it to the next two meetings; in lieu of this, we’re postponing the WG meetings until June. If anyone would like to have a Marketing WG in the meantime, reach out to @jdorfman.