I would HIGHLY recommend anyone deciding to carry on school property talk to an attorney who knows firearm laws.
The law was amended after Lopez and since amended has not been over turned.
There are exceptions, your attorney can give you the best advice regarding those exceptions.
One exception that is simple to understand is:
(iii) that is— (I) not loaded; and (II) in a locked container, or a locked firearms rack that is on a motor vehicle
I spend a lot of time attending my granddaughter's volleyball and basketball games throughout the state. I keep a pistol box and lock in the truck, and simply unload, and lock up my revolver prior to entering the school grounds.
That simple plan (according to every attorney I've talked to) would make it hard for any prosecutor to go after you.
But, as I said, talk to an attorney. It could save you a lot of heart ache.
Remember right, wrong, or indifferent, its gonna cost you a mint in attorney fees to fight the charge. The question is, IS IT WORTH IT.