Three avenues, Rimmer Bros, ebay and Towsure or Towequipe. A detachable will be more costly but agree it would look better. My Calibra had one and I took this off when not required and the sockets were behind the valance.
Ebay and
Towsure might be of the fixed neck design, Rimmer Bros may have the one you need.
Towequipe have a detachable version.