I live next to Yosemite and see quite a few truck campers in the RV mix that rolls through town. I would guess that 90%+ of them are technically overweight. You are not over what the axle can handle, what the brakes can handle, or what the transmission or leaf springs and shocks can handle. You are overweight because the engineers at Ford decided that the truck, as a whole, should only carry N amount of weight in the bed due to handling and stability, liability, etc.
In my opinion, in order to do this safely in a 3/4 ton (and up) truck, you need several things.
1. Your tires are the weakest link. Make sure that they are E rated, in good or better condition, and visit the scales to make sure that you are not overloading them.
2. A camper makes you top heavy. Do these two things to keep the sway in check. First, install adjustable shocks and set them on thier firmest setting while loaded. Second, if your truck did not come from the factory with front and rear anti-sway bars, visit a wrecking yard or the aftermarket and install a set. If your truck does have anti-sway bars and it is older than about 6 years, replace the factory worn out rubber anti-sway bar bushings with the polyurethane kind.
3. When your truck is loaded heavy and is nose high, the front axle is rotated backwards on its axis. This affects the caster angle and will cause your already different handling truck to wander. Install air bags. This will level the truck and keep the caster angle of the front axle closer to stock specs.
4. Center of gravity. Weigh the truck unloaded at the truck scales. Add the camper, and weigh it again. If you lost weight on the front axle, the majority of the weight of your camper is behind you rear axle. To fix this, you need to make sure that you have everything possible in front of the rear axle (RV batteries, food, fresh water tank full, and waste water empty, etc). If you are still tail heavy, SELL IT AND BUY A DIFFERENT CAMPER!
5. Drive it like an RV. If you use your SuperDuty as a daily driver, and you are used to how it handles, forget everything you know and get ready for a new lesson. You are now wider, heavier, and top heavy. If you can forget about how great your truck is zipping in and out of traffic on the way to work, and drive it like the RV it now is, you will dramatically reduce the chances of getting bit by being overweight.
Truck campers are great, and I have taken mine to remote locations that a travel trailer or 5th wheel could never go. And from the above info, you can see the reason why duallys are prefered over SRW. Just remember that you are overweight, and that ultimately
YOU are responsible for your rig and what you put in it and on it.
Here is a teaser shot of a guy with a DuraMax on the colorado river with a lighter weight pop-up camper.