Yeah...

Eliminate the sloppy tail wheel.

At worst use something like this:

http://www2.towerhobbies.com/cgi-bin...?&I=LXLGN7&P=7

Position it so you get ample movement of the tail wheel when the rudder moves.

Set the rudder to the highest recommended rate and then use at most 15% expo on it.

This will permit you to easily track down the runway with adecuate "authority". Too much Expo will tend to make it difficult to control on the ground...

You'll find that the plane will be MUCH improved this way.