FWIW huge boards are pretty common, used for maximizing donations and representation of various constituencies, in theory, but work done by small committee(s). Off the top of my head see https://www.sfmoma.org/about/about_bot and http://www.spur.org/about/leadership
Error at top of http://web.archive.org/web/20150809015937/http://ventureforamerica.org/
Error at top of http://web.archive.org/web/20150809015937/http://ventureforamerica.org/