Shutting Wednesday would be madness. That means everyone trying to arrive Thursday so would be complete grid lock. These early days help to ease traffic.
Theres a potential but controversial solution. Do early bird tickets for non coach arrivals. This could be done by vastly increasing the car parking ticket if you want to arrive on Wednesday with only limited numbers available bought at time of balance payment.
It would ease the strain to spread the load on Wednesday so not as many people on site initially.
People already taking the green option by using coach or won’t be hit by additional costs so this will encourage more people to be environmentally conscious and also bring in some more income for the festival.