I have a solution that you should consider. Think of the flap mechinism on a Ziroli T-6. Got it? Good.

Rear of the cockpit, build a tube-in-bearing rod running horizontally across the fuse approximately the width of the canopy. (think torque tube) It could be a tube in a close fitting tube or you could make the bearings out of 1/8th plywood. Wood is best due to metal to metal contact issues. You can make 2, 3 or 4 bearings. The bearings are nothing more than 1/8th ply cut to mount the torque tube in place with a hole in it. Tight enough to reduce slop, loose enough that the tube rotates freely. More bearings reduce friction, to a point. Again, think of the flap activation mechinism in a T-6.

Centered on this rotating tube (torque tube) is your control arm. This will be connected by a short length of rod to your servo arm. The servo can be mounted anywhere. Front, under, behind the horizontal rod (torque tube) you just built.

Now, on the outer ends of your torque tube is one control horn at each end. This can be a soldered brass piece fitted over each end using a hole drilled in it and soldered/brazed into place. Or, it could be a nose wheel control arm with a set screw to hold it in position. If using the later be careful. Replace the set screw with a long bolt and have it go through the tube with a drilled hole, The usual set screw will bend the tube and not hold well.

From here it is a matter of building a control attach point on your canopy. A tab on either side of the canopy will attach by a servo rod to the control horns on the outside ends of your torque tube. Instead of activating flaps, you are now moving your canopy.