Hobby team getting too many members

I‘d like to ask for some advice.

I play in a mixed hobby team with ages ranging from 20 to 80. We play at a pretty mediocre level and always do the same thing: solo warm up, duo warm up, attacking drills and then games (around 5). You‘d be surprised by our 80yo player who jumps around and throws himself after the ball. I‘ve given up on actually doing some kind of training and enjoy the games. Recently we are getting more and more members, about five years ago I joined and we were around 10 people, but mainly played 3v3/4v4 (because a few were always out), last year we got a few more and were tending to 5v5 and 6v6. That‘s good, but as of now we are playing 7v7/8v8 and it‘s horrible. We don’t play with a system and you won’t get a bunch of 60yo’s to start learning one. So it’s just waiting around for 1-2 rotations until one can play again. That might be fine if you’re playing at a high level and expending a lot of energy, but we simply don’t. We don’t have a proper trainer, simply two people who bring the keys and one of them makes the teams. He‘s supposed to allow the new people to join if we‘re less than 12, but tell the newer players that they can’t join if we‘d go over. But he‘s a complete pushover. I don’t see the situation getting better by itself by a number of players dropping out by themselves (out of disinterest, moving etc).
We don’t have more space to divide up our group and I don’t think our trainer would anyways.

Do you have any ideas or advice that can help in this situation?