There are all kind of ways to go about your issue. Do you want to keep your 5th hitch that you have now?
1..You can go with a Turnover ball installed in the truck. From that you could do any of the hitches designed for that.
https://www.etrailer.com/dept-pg-Goo...ck%20-%20B%26W
2...If you go Turnover ball you could buy an adapter and keep your old hitch. Like:
https://www.curtmfg.com/5th-wheel/gooseneck-adapters/x5
3..Turnover ball to Goosebox. Which given your situation I would consider.
4..Install factory puck system go whatever direction.
I think I would do some pricing and go with the best deal.