I have always spaced them just the same as any CA or klett type hinge.

Epoxy is just great and an easy way to use it is to coat the hinge area with some Vaseline (don't get it on the 'spike' ends that will be epoxied) then glue one side first to either the trailing edge or the control surface. After the epoxy has set it's easy to install the other side. - Watch the gaps between the surfaces and recess the hinges a bit to keep the gap to a minimum.

While you're at it check out the Robart hinges with a control horn on one half. They give a strong control attachment that doesn't have exposed screws on the top surfaces.

quint