Several points:
My wife and I normally like to make prior reservations so we know we won't have to hunt for a place when we want to stop, and luckily for us with are both in agreement with that
Maybe you should give in to hubby and wing it this time and see what happens. It might end up so bad that in the future he will gladly let you make prior reservations
When we did our four month Alaska trip, we almost always made reservations at least a day ahead of time, and I know we would have been in trouble if we waited until the afternoon on the day we wanted a RV park.
Good luck
Jack L