If you build the control surfaces with zero gap you do not need to mess with trying to seal them with MonoKote
This kind of thinking is like.............I screwed my motor bolts in tight, so I don't need locktite.
Even the faintest gap lets air flow through.......which over time could cause flutter or worse seperation. I seal every hinge.......its easy and cheap to do.
I used 3M tape (Dubro is now selling it) to seal my hinges. Its really flexable and can be re-applied until you really smooth it out.