The F250 will do great loaded up to 7000 lbs on the rear axle with 3640 lb rated tires on OEM 18" rims and the camper package which gives you the upper overload spring and rear stabilizer bar. Since the rear is not raked up like the F350, you do need address rear sag more by adding upper and lower StableLoads.
This truck is capable of more rear axle weight, but at this point you need to put too much money in to it unless you already have the truck and plan to keep it for a while. If buying a truck, that 7000 lbs RAW is the cutoff to start looking at DRW options. BTW: The last time I checked, the F350 DRW sits as low as the F250 but is wider. If you are set on keeping a F250 and want it to do more, adding 19.5" wheels, air bags and heavier dampened shocks to the already installed StableLoads will get you a modified 9000 lb RAWR.