Kids are like puppies, tons of energy and can't stay focused. I found through the years raising kids, coaching and training puppies and dogs is to give them tasks and rewards. Have them pick up around the campsite, have them gather twigs for a fire, have them help you set up, carefully watching every move. It take so much longer, but in looking back when we took our 2 year old and 5 year old camping all the time, constructive little tasks not only kept them busy but they loved it and still to this day talk about it, both now in mid 30s.
Don't wait, do it now, go out and camp
2020 28' Twin Flying Cloud-(Our 5th Airstream)
USAF Master Training Instructor (TI) - 68-72