a hitch extension is not the answer to the problem... if the trailer tongue is less than 50 inches, the front corner of the trailer could contact the coach when turning around.
a hitch extension is good to use if on your coach, you have a bumper mounted spare tire above the hitch... the hitch extension moves the hitch ball back out from under the tire so its easier to hook the trailer up... but it DOES NOT do the same as a longer trailer tongue.
behind a pickup, a shorter trailer tongue can be ok, but a motor coach has so much rear overhang, is very easy to jack knife the trailer when turning around...