By the book you might end up close to the limit, but you can run an F250 right at the limit all day every day. That's what it's designed to do.
The problem with an SRW F350 is that you could be looking for a long long time to find one. Especially this time of year. It will depend on what truck sales are like in your area, but around here nearly all the F350's on the lots are DRW. Very few are SRW. Plenty of F250's to be had though. To me that is a silent admission from Ford that there really isn't that much difference between the F250 and F350 SRW.