Mike, I have the same problem and haven't had any better luck than you. When I was at Trinidad we had a dedicated 'taper' lathe that had a spring-loaded roller follower mounted on the saddle on the back side of the tool post and it did help, but didn't completely solve the problem. The spring tension was quite high, I recall. A fellow on another forum recently reminded me about a u-shaped tool holder/tool system that would also add springiness to the cutting edge itself, and then (DUH!) I remembered reading about it one of the Machinery manuals. I've considered using my steady-rest to choke up on the length but that would leave a transition area in the middle that would be difficult to hide. I don't do nearly as many barrels as you so it's not an earthshaking issue with me but it sure is a PITA.
Good luck and regards, Joe
