The sticker in the door tells you exactly how much you can put in the truck - but "IN" is usually what confuses people. Because the tongue weight is not "in" but "on" the truck even though it comes off you GVWR. <--- strictly speaking of hitch trailers.
Your truck has a GVWR, I always tell people to weigh your truck as you drive it around. I.E. all the crap in there that you would otherwise ignore, like change, tools, stuff in the cubby, arm rest under the seats... some people would be surprised how fast that adds up, especially on a Ram 1500 that only has 1100lbs of payload.
So now you got a "real" weight of your truck, take your passengers weight and your tongue weight and add them up. The Payload goes FAST!
EDIT: remember GVWR is a vehicle off the assembly line (before you put your crap in it) with full, fluids - including full tank of gas.