I used to travel all the time with two cats but they started when they were kittens so it was part of their routine. If your little ones aren't used to traveling, you may be in for a difficult time. It will also take some time for adjustment after you get to your camp site.
My biggest concern is always "what if"? they get loose. Take extra precautions to make them as safe as possible and one important thing is if you are going to put them on a leash at any time they would be safer in harnesses rather than collars. Make the best of it and enjoy that you are doing your best for them. Keep calm and double check everything.
peace