With the rudder fully deflected and a brief burst of power, the aircraft should be steerable. I don't expect it to be easy, but it should be possible. At present it's only just possible with some forward speed and on very smooth grass or tarmac.

In contrast the Camel is quite easy to taxi. I notice the tail skid does deflect once a turn is established, as it should. The SPAD's skid also had some rubber compliance, it wasn't a rigid block of wood as it appears in the sim. Making it possible to taxi using a burst of power, rather than forward speed, would make the aircraft more satisfying to fly rather than starting and ending each flight on the runway.

Kevin