Have observers in the crowds who can notify the cp where there is trouble and a quick reaction security force can react.
They can also have roving patrols of 4-6 big guys.
They are marked as SECURITY, they are armed and they have video cameras.
Better yet hire a private security concern like Xi, former Blackwater since it's obvious the cops aren't going to intervene.
Most folks arrive alone or in small groups, park and walk to the venue. Since they have to go through SS security to enter the thugs know they will be unarmed to and from the venue.
Better to travel in larger groups, as Sheriff Clark says, with some large males that have thrown punches before.
Have self defense weapons in your car. Do not stop your vehicle for rioters, it's only a matter of time before they start dragging people out of vehicles. Do not get out of your vehicle to confront them.
This is only going to escalate until Cleveland when it will nova then super nova when Trump wins.
Be armed and be situationally aware at all times.