We have several F250-F550 trucks and the latest one in the fleet is a SRW F350 6.7. It is the best all around truck we have ever had and handles heavy loads easily with great handling. Got the SRW due to multiple uses for the truck and have the 20 inch wheels/tires. Plenty of margin for the toy haulers loaded up. I think you can make any of the trucks work if properly equipped from the factory for the load you want to tow/haul and some after market items can help as well.
It is going to cost money to do it right no matter what truck you get. As noted there will be some bargains out there as the new Ford Diesel is going to catch on. We have used ours down to -14F and it starts like a dream setting in a parking lot. (don't like to do that and would have plugged it in at home) Fuel economy is the best of any of the Ford Diesel we have ever owned and it is much quieter. Almost as quiet as a gas rig. If you haven't drove one get out and try them. If you buy one be sure to get the Mirror options, that alone is worth trading up.
It is going to cost money to do it right no matter what truck you get. As noted there will be some bargains out there as the new Ford Diesel is going to catch on. We have used ours down to -14F and it starts like a dream setting in a parking lot. (don't like to do that and would have plugged it in at home) Fuel economy is the best of any of the Ford Diesel we have ever owned and it is much quieter. Almost as quiet as a gas rig. If you haven't drove one get out and try them. If you buy one be sure to get the Mirror options, that alone is worth trading up.