We at Agaric would be very interested in helping with this whatever technology stack we go with. We have done CiviCRM for clients on-and-off for more than a dozen years, and are starting to move from experimenting with it for ourselves to actually using it.
A local real estate investment cooperative, Minneapolis Northside Investment Cooperative Enterprise recently asked me about somewhat similar needs. I mentioned Tendenci as probably the most out-of-the-box libre software solution.
But this is all very much a need of mass-base cooperatives, including cooperative platforms, and we have strong interest in serving this space including for initiatives we are involved, such as Meet.coop, Social.coop, and offering websites as a service, cooperatively owned and LibreSaaS, one of the initial and still slow-burning visions of Drutopia.