Just run the course first and see how you feel about it. You're the one that makes the call, and it will come from your Heart. If it's mellow then he'll probably enjoy it, and if it's not, you won't feel comfortable taking him. Another idea for side to side motion is to roll up a couple of his little shirts along side his head (if you don't have the fancy stuff) and adjust the carseat until it is tilted back as far as it goes.
I'd make Daddy ride back there too. But that's just me.
Have fun!