Modifying mixer file without reflashing

I am writing a custom airframe and mixer. (see http://discuss.px4.io/t/adding-new-airframe-to-px4-and-qgc/)

When i make changes to the mixer, I perform

make px4fmu_v2-default

and reupload the binary in QGC using custom firmware option. I find that I always need to rerun the entire sensor calibration process (even though the hardware didnt change). After calibration, QGC allows me to arm and fly.

I can see the mixer files in Pixhawk (via onboard files dialog in QGC), Can I edit them directly?

Ziyang