I helped a friend load his camper. We used a cordless drill to run the jacks down to the ground. Once the jacks were on the ground we each used a hand crank handle and worked the rear jacks a certain number of cranks, then the front, and we alternated front to rear, running each the same number of cranks, keeping the camper level side to side since both rear were operated in tandem, then the front.
Growing up, my dad had several truck campers. They were hydraulic, not crank, and we'd operate them the same - alternate front to rear. (two people)