Huckfin, Your sketch idea will work well. You do not need a come-a-long. Here is a little secret for loading heavy objects on and off your truck. Use gravity. Load the camper down hill. Once you have it safely on the truck, pull to a place where the truck bed is tilted down hill and you can easily slide the camper on where you wish. The same goes for unloading. Unload your camper down hill if you are sliding it. You can jack up the front wheels of the truck and slide the camper right off. Ramps? I'm not suggesting you actually do that.
This an exaggeration to make a point to always use gravity as your friend and avoid fighting it. It is the same thing as when you get your truck stuck. Experienced off roaders know to use the tow strap down hill, if practical. Gravity is surprisingly powerful. Novices will observe how smart you are, or how strong you are, when all you are actually doing is using gravity as your friend. John D
This an exaggeration to make a point to always use gravity as your friend and avoid fighting it. It is the same thing as when you get your truck stuck. Experienced off roaders know to use the tow strap down hill, if practical. Gravity is surprisingly powerful. Novices will observe how smart you are, or how strong you are, when all you are actually doing is using gravity as your friend. John D