Ever wonder why the kids are a little happier after camping. Fight nice kids, that's what I always use to say. Of course a little challenge here is not a fist fight.
Take the phone away or at least get there attention when they first get to camp. Sure they don't want to do things your way.
Once the kids figure it out, that they just can't be doing actionable things on that phone. Like rowing a canoe or play physical games with new friends in an open field.
Actually, they will find out that they have more room to roam and explore at camp then at home. The lake, water sports, hiking and cruising around on their bikes will become second nature.
Speaking of second nature, what are you doing later? Yes, you will miss the kids a little, when it's quite and no body is buggy you cause they are bored.
Fight nice simply means that I will challenge you, because I'm pretty sure I can do that thing faster than you.
I'll race you for it!