Most gooseneck hitches can usually be swapped for 5th wheel plates & vice versa. While the statement is true that bumper pulls are easier to sell. There is a huge market for goose necks and 5th wheel cargo trailers. Many weekend race car people use them, along with souvenir sellers. And other car hobbyist. Never seen a farmer around here have an enclosed cargo trailer usually they are either cattle trailers or open flat trailers.
Have you considered a gently used tractor trailer / trailer. The size & terrain of your lot will determine the possibility. It does limit the movement to a truck tractor or heavy equipment. Grant you can't move it easily but a used shipping container is probably the cheapest route. Side it and use it as a cabin later. :).