would it be worth neutering my F450 from a 4.88 to a 4.10

4.88 is for 1st gear launch power. Unless you're launching heavy up steep grades or carrying a heavy box around town all day, it's highly unnecessary. Personally, I'd prefer a 3.55 ratio for a 12k lb 5th wheel. 1750rpm at 65mph with the diesel is about right. Downshift when needed and get better mileage on the flats and running empty.