Camping is meant to be relaxing, casual and fuss free. If you are very insecure, then take a small bag of essentials and pare down your look to a few basics, maybe a bit of powder, a light dust of eye shadow a brush of waterproof mascara and no more. Do be sure to wear a lip gloss or balm with UVA/UVB sunscreen, this is extremely important. use a moisturizer with sunscreen on your face, also important. Don't wear perfumes, body sprays, or scented lotions and moisturizers. You will attract biting and stinging insects because you will smell like a flower. As for the hair, don't worry about it. Let it go natural, you can have a wild and untamed jungle girl look, guys like that and who knows, you might find you like that look better, too. Be aware that make-up will not last while hiking, biking, canoing, swimming, etc. Maybe you should try to take a vacation from your rigid hair and make-up routine, you might enjoy yourself more if you worry about your appearance less. You're probably fine without make-up, you just don't realize it. Remember, no one else will be made up or doing their hair either.
I've been camping since I was quite young and I always get a chuckle out of what I call the mirror girls. These are girls that plant themselves in the campground washroom in front of the mirrors for at least two hours every morning, They spend so much time focused on themselves they miss out on all the fun. Try not to focus on outside appearance and open yourself up to some new and interesting experiences.