Develop inhouse teams is the best way to go, but you'll need to coordinate with the league operators. In my case I have eight teams on Tuesday that are all inhouse. I believe my operators have set a minimum of six teams for in-house league.
APA is very strong (188 teams) in North Alabama and I compete with a few small bar venues and four other halls with 10 or more tables, three with all Diamonds. The others and I have Valleys. I've not had any complaints about charging a $5.00 green fee per team and the other halls do the same during league.