I might be persuaded to help a few local folks such as yourself.
I wrote software that runs on a microcontroller (think Arduino, but not using an arduino hardware-wise) there is a small board that is reading the analog voltage values directly from the stalks and turning those analog values into digital 'positions'. So when I read 1.8 volts, the turn stalk is in the middle (normal resting). when i read > 1.8 but < 2.2, it is in the half-up position. above 2.2v it is fully up. I then take those messages and turn them into CAN bus messages that the car understands, so that it starts blinking the signal.
It sounds complicated, but isn't very. The only tricky part was figuring out which pins/lines I needed to read on the stalk ribbon cables to get the values I needed to read them.
The nice thing about this approach is that nothing in the car is modified. Software updates to the car will work without issue, and the mod is mostly undetectable when you aren't actively using a turn signal or other control that has been added in this fashion. Even then, i highly doubt tesla cares.