I've seen one plane, a top-hinged Mustang, fly with more precise aileron control after covering the bottom gap with a strip of clear plastic (adhered in front of the aileron.) I have not seen such dramatic results from other various seal operations. I question whether, at the slow speeds I fly, much need for sealing control hinge lines exists.

I have seen control surface forces increase, when Monocote is used to seal a hinge line, taxing the servo and receiver battery.

For these reasons, I do not fret about sealing hinge lines. (I do, however, take care to minimize the gap at hinge lines.)

Good luck,
Dave Olson