I was thinking something similiar.
To be honest, I voted no and I really dont want to see this implemented for all the reasons already mentioned, but if it were to be implemented with all the restrictions BB-Marin has wrote, then I dont think it should be free for supporters nor be only for supporters.
the only way id want to see it implemented is as a one time payment. Whether you are supporter or not, pay $10, for a second team(only once) and itll still be connected to your primary team and all the restrictions will still apply, but youll just have a second team. Thatll also help with the constant league and team shifting that would happen due to peoples supporter running out. I just feel like theres gonna be a lot of inactive second teams while people are waiting to renew their supporter and thatll just make the use of a second team a waste. If you make it a one time purchase of $10 or maybe more or less then people who buy it would be people who would be serious about their second team, so that would eliminate some farm team possibilities(not all but some), it would maintain the competitive side to it because people paid so they are going take it seriously and dont have to worry about it the team just going inactive in 90 days when their supporter runs out.
I also would want to see it in a world league set up.