Lots of people will tell you lots of things. IMO, you should arm yourself with an education of what the various numbers mean and how they apply to each other. Then, you can decide if you're going to be within your ratings or will end up exceeding them; and if you do exceed them, are you comfortable with it?
I'm of the camp that wants to be within all of my truck and camper's ratings. The one rating that is most usually crossed is the GVWR (gross vehicle weight rating). This is the maximum that your truck should carry. This includes everything from the weight of the truck itself to the driver and all occupants to everything you carry with you and then eventually 20%-25% of the camper's loaded weight in the form of pin weight.
For the loaded weight, the most conservative thing to go by is the GVWR of the camper. You're unlikely to reach it in many cases, though. But like I said- it's the easiest and most conservative # to go with. OR- it is told that the average RVer adds 1,000-1,500 pounds of stuff above the dry weight of the camper. Seems like a lot, but the dry weight doesn't include necessities like propane or battery, etc. It all adds up!
Figure out your payload (the GVWR minus the weights of your truck and everything it's carrying) and see if you have enough left over for the projected pin weight of the camper.