Are you planning on getting a dually? The single rear wheel truck 2004 and earlier only has a 9,900 GVWR, and that is not enough to have the 400 pound diesel option and still have enough cargo rating to carry a camper. If you also plan on having a crewcab and 4 wheel drive, you will be really overloading the truck even before loading it with camping supplies. The dually will have plenty of cargo rating for the light camper that you have selected.
So your plan is to build a platform between the cab and camper about 2' long to prevent the camper from going to far forward in your bed? I have heard of people building such a thing, and using the space to hold their generator, firewood and such. THey also added doors, so there would not be a "gap".
However that might put the camper center of gravity further back over the rear axle, farther back than designed. With a dually, it will not matter, however with 16" rims and 3,042 pound rated tires (235/85R16E is standard with that truck) you might overload them. Moving the load forward even 12" will put much more of the weight on the front axle, and not also be taking weight off the front axle by having more hanging off the back of the truck.
If it is a single rear wheel truck, then be sure to check the weight of the truck before buying it. If the GVWR is only about 2,000 pounds more than the truck, it might be as overloaded as a F-250 with a gas engine.
Fred.
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