I, too, am a firm believer in horses, girls and camping.
When my daughter was about 9, she and her best friend approached "the Mom's" and asked about a mother-daughter overnight pack trip. The first trip was one night with what we could each pack on our horse. We learned A LOT!
Subsequent trips (9 in all) used at least one pack horse.
I remember on the first couple of years (we did this yearly) at some point during the trip, the other mother and I would look at each other and say, "Not again. I'm not going through this again", usually referring to pre-teen attitude. But every fall, the girls would suddenly pipe up, "Hey, Mom, where are we going to go on the Mother-Daughter ride next year?" Kathy and I decided that as long as the girls wanted to ride/camp with us, we would take them wherever they wanted to go. We ended up doing these trips for 9 years.
The girls are 22 and 23. One is in vet school; the other works at a vet clinic and will get married next summer. Both still LOVE their horses and riding and want to camp/pack whenever possible.
In my experience and opinion, you can't go wrong with the great outdoors. Even when the attitude gets to you, hang in there. Chances are the memories of the trip--the experience as a whole--will vastly outweigh individual moments and the girls and you will be enthusiastically awaiting the next trip!
The trail is the thing....Louis L'Amour