I guess the ultimate, and   not too expensive  fix would be a  simple 2 or 3 bolt sheet metal flanged bearing.   Open up the  through hole a little with a die grinder, so the   flange would  sit  flat against the  neck.. and   drill the holes for the flanges. 
I'm guessing the   shaft is  a common size,  1 inch perhaps?
My trailers  only have a  simple dry tube  welded  at that spot,  and  when i'm  walking around the trailer with my  squirt bottle of   hub oil,   I'll  hit that  noise maker  on the way by.   But my trailers aren't near as  spiffy as  that one!