My teenagers and I are hiking for about a week in West Virginia and northern Virginia. They would like to bring our 3 month old lab mix puppy. She is about 20 pounds, in good health, good personality, will be leashed. We'll carry her food and water. We have no need to go far or fast, so if she slows us down it's okay. Is this crazy? Would it be harmful to her growth and development? I'm having trouble finding good info on this.