Unfortunately because of the behaviour of a few idiots action will be taken. Policing/stewarding is never going to stop a determined invasion. So all you can do is start making an example. It's already an offence to go on the pitch so next time it happens a random 10 say pitch invaders (substitute a number of your choice) are banned/prosecuted or what ever punishment is seen fit. Next time there's an invasion twice as many fans and so on (except of course if you are attacking Billy Sharpe).
I know this maybe seen as typical old fart talk but the last thing I want is to be watching football through a fence.