RE: Acceptable aileron hinge gap for a Trainer?
Really, either fix will work, but Darock's is a more proper way to do it as it will put the torque rod on the hinge line.
Time Pilot, Use the 3/32" sheet you have and do it like you said (Cut a groove, slide it under the torque rod, and glue it to the Trailing edge)
Covering should go UNDER the torque rod, not over it.