I have exactly what you're looking for:
MBBA
No current open teams, but we tend to have 1-2 openings a season, and at some point (probabyl next season) i want to open up the subleagues to ownership which would give me like 50 openings.
Best to get in ahead of time anyways, because we're a pretty complex league and it's a lot to take in.
Hope to see you there. Shoot me questions via PM if you have any.