I had a similar truck, and ran a truck camper. Mine was a 2003 Hemi 2wd short-bed 2500. I found that I had around 3000 lbs of payload from dead empty, my camper was about 1800 lbs wet, I ran with around 800 lbs of tongue weight from a trailer and the rest was us, luggage, gas, etc. The truck was fairly happy at that weight, but got bad fuel mileage - as low as 7.5 mpg. I did nothing to modify my truck, being of the mind to stay within - barely within, but within - it's GVWR. I was around 2,000 lbs over on the combined weight including the trailer, but within the recommended combined weight for the 4.1 diff option (I had the 3.7 diff).
My recommendation is look smaller rather than larger, and try to stay within the truck's GVWR. My camper was 8 foot on a 6.5 foot bed, I would look for an 8 foot to 10 foot max camper in the 2400 lbs wet range. Means leaving out some luxuries - my camper did not have any kind of a bathroom.
Brian
2005 F250 Supercab, Powerstroke, 5 speed automatic, 3.73 gears.
20 ft race car hauler, Lola T440 Formula Ford, NTM MK4 Sports Racer
1980 MCI MC-5C highway coach conversion
2004 Travelhawk 8' Truck Camper