Look in the glove box for a weight sticker. This takes into consideration the options on your truck and is a better indication of it's load carrying abilities than the door post sticker which is very generic. One thing to consider though is the glove box sticker assumes a 150 lb person sitting in every seat. So if you have a crew cab and nobody rides in the back seat, add 450 lbs to that weight.
If you're within 60-70 lbs of the door pillar weight and the camper's sticker weight, you're in better shape than most here and I would think you're good to go.