Aloha Tom,
Tips for young kids...
Let em play outside. Tell them to stay away from the fire pit, give them boundaries and keep a close eye on them. Especially when they are that young. The babies, we just let them play in the grass. They love it. The older kids will also play with the little ones. The little ones play with each other too, but they like just hanging out. It's relaxing and helps to get them tired at the same time. Then when they go in the tent, they sleep.
Oh, try to keep their routine. That's why we pack books and pads and pencils and such. Stuff to keep them busy if it storms and they have to stay in, just like home. The great thing is the kids don't need TV!!
I sunscreen my kids first thing in the morning and touch up a couple of times during the day. If there are a lot of bugs, I will bug spray them a little.
Other tips...
Keep them watered a lot and fed a little. They will munch on stuff on their own constantly anyway. I monitor their bathroom activities to make sure they are drinking enough and every hour I call them to come and drink water.
Have other kids there. They are happy in their own little worlds playing with their friends. We stop their play to impose discipline when needed. I always tell them to make sure they can see us and we can see them.
Finally let them go and play. Sometime parents worry too much. On another trip, one of the moms that I invited brought her special needs child. Neither had ever gone camping before and mom was really worried especially about her daughter's behavior situation. I told her she is just another kid and will be treated the same as all the rest. The daughter had a great time and so did the mom. And not only that, her behavior was great. The daughter's was too.