My children now have their own kids! When my daughter was 5 we did a backpack in the Wind Rivers. I hired a horse-packer to take us in about 7 miles and she rode a horse and I walked. We then spent one day at a nice lake and two days walking out, downhill. She carried the pots and pans and loved to make them clang when she walked. I chose late season so there would be no mosquitoes and lots of berry gathering and less dangerous water conditions. We spent several hours gathering whortleberries (very tiny) and then made a pie. We built fires every night. Rather than just ordinary backpack food, I brought a frypan and lid to bake in. We made cakes and cinnamonn roll. She liked to cook, fish and gather berries. Few kids are thrilled with the walking, but most like to explore and do things in the mountains. Back in those days there were no light weight kids cameras- but that is a great idea. You have to set the mood too - assuring, happy and fun. Also, this was not her first trip. We had done several shorter trips in the past. Her first backpack was a week when she was 17 months old. Again, we utilized a commercial packer and she rode a horse (on the lap of an adult family member). We walked out and I carried her in my backpack. I think the key is to simply get them into the woods early, whether backpacking or not, so it is a familiar environment for them.