Based on the available information, the County Highway 6D boat ramp in Fall River County, South Dakota is a public boat ramp that provides access to a body of water, likely a river or a lake. The coordinates provided indicate that the boat ramp is located at latitude 43.28231049 and longitude -103.44799042.

Unfortunately, there is no information available on the width of the boat ramp or the type of craft that are allowed on the water. It is important to note that regulations and restrictions on boating activities can vary depending on the specific body of water and the local authorities responsible for managing it.

To obtain the latest information on the County Highway 6D boat ramp and the body of water it services, it would be best to contact the local or state agency responsible for managing boating activities in Fall River County. This could include the South Dakota Game, Fish, and Parks department or the Fall River County Sheriff's Office.