Lets Clarify: F250 Fifth Wheel Set-up

First, welcome to the forum! Glad you decided to step out of the shadows! To your question, imo you're going to be right on the edge of capability, or just beyond. Assuming all your figures are correct, you will have very little room for additional weight, forespecially pin weight. I don't know what effect the short bed has, but I've personally always preferred the longer wheelbase for improved stability. You'll have to carefully pack, and get it weighed to insure your pin weight doesn't creep up any higher.