My $25 trim position indicator system moves full scale when the stab moves from full up to full down. It is sensitive enough to register stab movement of 1/8 inch. The scissor link has almost zero lash. Repeatability is highly accurate.
Because the trim motor is a bit fast for my taste I am wiring up a pulse width modulated speed reduction to add to the trim motor circuit. That should make the trim a bit less sensitive in cruise and still give near full torque to the trim motor. (If one were to add a resistor to simply drop the voltage, the motor would lose too much power.)
I agree you should have a reference stripe on the stab/fuselage to compare with the gauge on preflight. Once the gauge is deemed accurate, you can reset the trim for takeoff using the gauge when you do full stop landings and depart again.
John Pitkin
Greenville, TX