The F250 with the diesel has almost no payload, less than my 1500. You can argue that it's artificially limited by the GVWR number, but if you want to stay within the letter of the law then go F350 SRW if you want to go diesel.
FYI.....GVWR or gvwr based payloads does not determine how much load a truck can carry legally or safely. There is no laws regarding vehicle mfg payloads or its gvwr as a legal load limit.
This is where any 3/4 ton with the bigger 6000-6500 RAWR can easily,safely/legally carry 3000-3500 lbs in the bed.