This probably isn't much help to you! I'm sure you plan on going back farther. My gooseneck ball is 8-inches behind the center of the rear axle on my 2007 3500 Dodge, I would have preferred it right over the center of the axle, but had to place it where the factory aluminum bed has the opening. I pull a 17,000-pound, 25-foot flatbed gooseneck with no problems. Knowing how well Fords can haul weight, and you'll only be towing 5,000-pounds I'll bet you can set it on the bumper and have no trouble, LOL!
Maybe you can experiment with a welder or two!

Oh and to add, they normally figure a properly loaded trailer only 20% of the gooseneck trailer's total weight is on the truck.

I have a 2008 Dodge Cab and Chassis. I pull a 40" Fifth Wheel with a 2500lbs. Tongue Weight. My Hitch as well as my Gooseneck Ball is mounted Two Foot behind my axle. It would have been back another twelve inches but I have a Dovetail on my bed. I have never had a problem with it set up like this. Most of the Welders I know will mount their Ball as far back as they can get it.

I agree with Johnyutah, why not just go bumper pull unless your going to upgrade in the future. I towed a 50 or 60 model 300M back from GA with mine and a bumper pull trailer and had no problems.

All you other guys, I can't believe you have your ball set back so far! You don't notice any light steering? Mine is set a few inches before my axle(but don't own a gooseneck either) I thought for sure set back that far you would notice a bit more skyward elevation! :-)