I've always thought it would be cool to have an interaction sign maybe 2 km away from the prison, have it so the prison is locked down and you can't get inside it to take defense as a rebel.
Cops have x amount of time to deploy to the prison like swat and then after the x amount of time passes, the prison can be attacked.
1 life only, cops can't come back and shoot the rebels in the back
This would obviously need alot of work to make it free of exploits.