Seems like a lot of different opinions here, so I'll add mine! I went to overnight camp when I was 6, almost 7. My sister who was older, also went, but we did not stay in the same cabin. I then went on to go to that camp, every year until I was out of college! As a camper, I only went for one week at a time, but I went for all the weeks as a counselor. As a counselor, I have seen kids who were 12 and not ready and seen kids who were 7 and ready to stay a month! So, it does depend on your child. I saw that a poster said not to listen to you child- well, she didn't say it in those words, but basically. I say the opposite, out of experience with 100s of kids. But, don't just listen to them now, when it sounds dreamy and fun, listen all the time. What you are doing in getting her ready is right- make sure she can wash her hair and brush her teeth, dress herself, etc. I'd pack her clothes in large zip-lock bags that have everything for the day in there. That helps a lot. In our camp, each cabin had one big shower and about 4 shower heads. We had 4 or 5 campers in there at a time, so they all helped each other. The counselors stayed close to make sure the water wasn't too hot and the girls had all the soap out of their hair and all that. Plus, I always made sure they brushed their teeth and were actually dry before getting into bed! I have nothing but good memories of camp- even the girls who were homesick usually ended up being fine. Most counselors will take mroe time with those and love on them more. As a counselor, I always wanted the youngest cabin because those were the sweet ones, even if a little homesick. There were many nights I fell asleep snuggled up holding one of my campers and reading or signing to them.
Also, as a camper, they really get to learn about themselves in a way that they can't at home. I was more independant, too. I learned how to brush my hair and all that. Of course, a 7 year old won't be able to do a perfect job, but that's what the counselors do, too.
BTW, my camp was also a YMCA camp, so they are pretty structured. In fact, one of the campers and then counselors I went to camp with all my life is now the director. I can't wait until my son is ready to go. Of course, that means when he's ready, not always just when he's 7, though. I think you'll know if she's ready. If she's whining when you leave, maybe she's not ready.