We were there for the 50th/60th/70th anniversaries. We used to stay for a month at a time, so were there well in advance. Plus, we visited Normandy every year for getting on for 20 years. It isn’t the easiest place to get around, think Cornwall. It was always rammed at anniversary time, not just with tourists, but all the dignitaries & associated security. We didn’t even try to take the car out for a couple of days either side of 6/6. Personally I wouldn’t go there at anniversary time now, it’s a much better place when it’s quiet. Your best bet would be to find a campsite away from the main areas & coast, and either cycle or walk in. We now prefer to head up towards the top of the Cherbourg peninsula, Barfleur is our favourite, can’t recommend Camping Blanche Nef enough. Probably the best municipal site you’ll ever visit.