Like you we looked very hard at weights. The camper we selected was a AF1150. To handle the weight we ended up with a 2013 F350 DRW 6.2l CC 4x4 Lariet with the camper option. The camper sticker that came with the truck said:

Which was down a fair amount from what the 5,969 lbs Ford Tow Guide (which has truck camper weights) had listed for my configuration. The difference is the options we had going from a base Xl. (Note the slide in weight rating includes 150 lb passengers). Our door sticker looks like:

Which is again down from the "max" payload table listed because of the options on the truck.
Regarding the campers, when all is said and done the rule of thumb about camper weight plus 1000 lbs is a pretty good one. Alternatively, look at what Truck Camper magazine does. They take the campers, add the weight of everything else, (Batteries etc.) add the weight of filling the tanks, and throw in 500 lbs of "stuff". That too provides a decent estimate. Here is their page with Lance estimates (notice the weight calculations):
Truck Camper Magazine Buyers Guide - LanceReturning to our example, the estimates worked pretty well for us. With 3 people, a lab, and our camper with full tanks we rolled up to a CAT scale and weighed in at 13,700 lbs or just under our 14,000 lb GVWR. We got enough truck for the AF 1150 and it handles the camper weight very well without having to worry about suspension modifications (we did add stable loads to it "level" on the truck.)