Your dealer provided remarkably good advice. You are also fortunate in having a 2016 year truck as that was the first year that Ford provided a much stronger truck frame.
Also check the tires on your truck. With my 2500 truck the factory tires had a load rating of 3095 lbs or 6190 for the two at the rear axle. The truck itself weighed 3200 lbs at the rear axle when empty. The weight of the truck and the camper was going to be more than 6200 lbs.
I replaced the factory tires with Nitto tires rated for 3750 lbs (similar tires fron Toyo and Goodrich) each and increase the load capacity at the rear to 7500 lbs which was more than enough. The local CAT scale costs about $15 to have the truck weighed with and without the camper and then you know exactly how much weight is being carried.
I discovered that 80% of the camper load was being supported by the rear wheels of the truck.
The Supersprings double leaf set (4 leaves in total) cost me $450 and provided the support needed for the heavy camper. They took me an hour to install and greatly improved the handling of the truck. In a turn more than 50% of the weight of the camper is being supported by the wheels on one side and so adding more support adds to the stability.
Another change I made was to replace the factory shocks with Rancho XL adjustable shocks. I found that having the front shocks at 5 and rear shocks at 10 provided the best ride with minimal porpoising. With the camper off the truck I would only change the rear shock setting taking them to 5 or 6. Thirty seconds and no tools needed to change the setting on the shocks.