This is a B&W Turnover Ball Hitch with their Companion 5th wheel adapter and used for pulling my 34 foot, 11,000 pound 5er. It can be either installed or removed in two pieces in 10-15 minutes leaving a perfectly clear bed. I even use mine with a bed mat that has a 4" hole.
As far as a goose neck adapter - call the trailer manufacturer and get his blessing. Mine said absolutely no.