Rooftents are pretty large and cumbersome. If you have a lift, you can disregard but if you are going to heft it up by hand, you have to get the weight down. It gets really noisy at the other end if you are lifting more than 50 pounds. Let's say you have a rooftent that is 115 pounds, like mine, take the mattress out. The mattress in my rooftent is 35 pounds so the tent now weighs 80 pounds, piece of cake.
If you are lifting it up by yourself, here is how I used to do it before I put up my lift. I would store the tent on a lift-truck. I have a Columbus so it is quite long and the bottom is totally flat with the mounting system moulded into the base. I would move the tent to the back of the truck, lean it against the hatchback and put a mover's blanket under to protect the paint. Simply lift and push from there. I used to have a big Maggiolina Adventure, one of the really old ones made out of polyester fiberglass, really heavy probably close to 200 pounds. Again, I would do the same thing and it was pretty easy. I would think that this is where the new carbon fiber tents shine, they are really light and if you drop it, so what, probably will hurt the floor though.
Rich H