Bob- My table post is made by Springfield, is also tapered on both ends and I have not been able to find a shorter version. My Siesta has a socket for the table for use when front chairs are rotated into the cabin and a shorter post would be ideal. I don't think the post can be turned down and posts at the dealer and West Marine are thin metal and not tapered..
Good luck -
U.S. Coast Guard retired- 1956-1985
Lily- the Pug
1972 Moto Guzzi Eldorado