Clamper

n. 1. One who lodges temporarily in a hut or camp, especially who sleeps in a wilderness for recreation. [ 1913 Webster ]

2. A person who stays at a summer camp or day camp. [ PJC ]

3. A vehicle, such as a small truck, or a pickup truck with a hood over the back, equipped for convenience while camping out. [ PJC ]

happy camper a person who is pleased with the situation in which s/he finds him/herself. Often used ironically or in understatement, especially in the negative; as, the passengers left behind on the island were not a bunch of happy campers. [ PJC ]