Only problem making the stick longer as the solution is that it makes you have your arm unsupported while holding on to the top of the extended stick. Not only is this very uncomfortable, but makes it difficult to be very accurate with your inputs on a plane that doesn't have high control surface loading like the KR2 and S. Several current KR pilost have stated that you want to have your arm supported and wrist fly the plane, which I agree with. Having your arm up in the air unsupported is like holding on to the top of a bus steering wheel while driving; you can do it, but it gets VERY old quickly. It is very akin to flying a helicopter which I have also done, which experience in the KR2 helped with. The whole flight range is about a 1/2" in every direction until just before landing.
Several of the original drawings lack something to be desired to put it nicely. Also, Ken was not good about updating the original plans with changes that he made to the original design, which is what makes the net so good. Follow what KR drivers are now flying with success and you will YEHAWWW much sooner... Colin N96TA