I copied this from the Assembly Manual, which is on the Pacific Aeromodel website. I guess they should have said that too much rudder will make the airplane uncontrollable on the ground also.
I had the same problem turning the airplane around on the runway with low rate rudder. My solution is to use the recommended high rate for slow speed taxiing and the recommended low rate for everything else.
For the tailwheel, you need to preload the springs when you install them. Bend the ends so that the spring is about ahalf inch or soshorter than the distance between the steering arms so that you have to stretch it to install it.Alonger steering arm on the bottom of the rudder will also help.
A gyro won't hurt, but basically you just need to cut down on your rudder throw.
SETTING UP THE CONTROLS
Ailerons 7/8” 1 1/8” up
1/2” 5/8” down
Elevators 1 1/8" 1 3/8"each way
Rudder 1”1 1/2” each way
Do not omit the aileron differential. The Monocoupe will not fly well without it.
We recommend Exponential on the elevators: 25% at low rate and 40% at high rate. We do not use Expo on any of the other controls. CAUTION: The rudder is extremely effective. Do not use more than the recommended travel on the rudder. High rudder deflections can make the airplane uncontrollable in the air.