Fireworks, Cannons and Cars

I want to surprise the kids with an early morning outing tomorrow to the local beach. There are these giant cannons at the beach, and the town will be firing them off tomorrow. I want to surprise the boys with this, but I can't. In our house, if we include Sammy, there can be no surprises. Not even good ones. He cannot take the pressure of it and it makes his anxiety sky rocket. I can't just prepare him because he doesn't understand how to keep secrets.

he dug a hole and stuck his head in...

I will tell him in the morning before we leave, but not too soon before. If he has too much time to think about it, he will melt. If I don't give him enough time, he will melt.
Holidays are just plain tough. You can see how much he wants to enjoy the fun. He wants to be part of it. Sometimes, he is wonderful. Sometimes he keeps it all together until we get in the car and then he melts down. Sometimes, he looses it right where we are and I can't do anything but hold him and protect him.

We will go tomorrow for 30 minutes. We will end on a good note. I will set my expectations as low as possible. Wish me luck!