Aileron Rigging vs Aileron Trim
I'm more of a flyer than a builder - and when it comes to my park flyers - I'm happy to get them built quickly, and work out the tiny details with software.... or in this case - Rotary Encoder S1 and S2 on my radio.

New built airplanes may not have the control arms set perfectly. I usually ensure my servos are centered during the build process, and then rig the control rod linkages to give me a neutral control surface close to that setting.
When I pair the model with the radio (every time I switch models - don't skimp on flight control checks.) I'll ensure my trims are centered, and then use S1 and S2 to give me the perfect rigging and trim. Here's how:
In my setup, S2 trims only the right hand elevator. S1 works as aileron trim. So I'll simply set S1 to where the left aileron is neutral, and use S2 to neutralize the right aileron. This way - despite having ailerons linkages not exactly perfect - you can always fix them in the field with no tools required.
When in flight, and working to fine tune aileron trim, you can simply slide your hand off the throttle, and rotate S1 with your left hand. Your right hand is still free to feel when control forces are neutralized. You shouldn't be making throttle changes while trimming these planes anyhow - active torque and speed changes only make it harder to accurately trim, until you really get a feel for your plane.

Same goes for pitch trim - I use my right trigger finger to actuate my right slider (RS) which I use as a fast pitch trim. (I use my left slider (LS) to actuate flaperons. More on this later).
It may not be the way everyone does it - but it makes trimming and rigging these planes simple and easy, and beats hunting for tiny trim switches in flight.
Works for me.