What I did in my RV-9
I just finished installing the electric trim in my RV-9. There was a little bit of "winging it", but basically I did the following:
*Checked the plans and drawings to ensure I installed the servo plates in the correct spot, and only riveted when I was sure it fitted properly.
*did lots of drilling and test fitting throughout
*Ensured the servo shaft and clevis didn't hit anything through full travel stroke (it didn't).
*Put snap bushing into the elevator spar hole
*held the trim tab in-trail with the elevator trailing edge
*Checked the length of the threaded rod between the servo & trim tab clevises, then cut it.
*wired up the switch, indicator, and servo (with a milwaukee 12v battery), drove the servo to the exact mid position THEN I cut the rod.
Finally I screwed and pinned everything together and tested again, checking that the servo electric cable didn't foul on the servo jackshaft. Re-checked for full range of movement without binding.
Lastly, can I say that I can't help it, I'm an Engineer. My wife knows it's a recognised condition.