We gently lean our canoe against the rear of the camper (with the tip of the boat on a foam pad the dog rides on), someone goes up the ladder, and it somehow gets there. We have Yakima clampy things (you'd naturally want the kayak version) on the factory-installed boat rack as well as foam blocks because our rack is only on the back half of the camper and it didn't seem right for a boat of any length.
It helps that our camper is a popup so it's not too tall, and that our canoe is only 50 lbs, but it is very awkward at 19 feet long so it takes a second person to guide it.
Over all, it goes up much nicer than I had anticipated. Check out some of the accessories that Thule and Yakima have. There are roller things, etc., but most do require a rack.