Scale Flaps
 

You can modify contrl horns for use as below the surface hinges. I've used that on an overweight .60 powered Kadet Sr. (I have pics... That should be close to the same size and weight.)
You can also cut the pieces needed from aircraft ply to get the exact configuration you want... Little pieces of brass tube for bushings and 2-56 screws, with aircraft nuts for the hinge pins.

The options are almost endless.

I'm procrastinating about reworking the Kadet... :rolleyes: Stalled on take-off last year.
( The flaps were not part of the cause, and weren't damaged. )

Scale Flaps
 

Just to expand a little on the previous...

Yep, done that, too. If you can't picture it, what you do is mount a control horn on the underside of wing's triling edge and one on the underside of the flap, ligning them up such that with the flap in place, one face of the wing-mounted horn is flat against one face of the flap-mounted horn and the last hole of the two horns are aligned.

Popping a screw and locknut through that last hole converts the horns into a hinge -- gives it a scissor action with the main parts of the horn shearing open and closed about the screw.

For control, you can either use another horn on the flap or, if you're careful, you can cut out pushrod hole area of the wing-mounted horn enough so that it doesn't interfer when you use an inner hole on the flap-mounted horn for a pushrod, ball-link, z-bend, or whatever.