I've done some research on this, it looks like I need downthrust! So on the bottom instead. Quote: Conclusion Even if we limit ourselves to pusher planes with the motor above the wing and behind the CG, there is no single answer to the question "what motor angle should be set for the plane to fly?". Depending on the design and the exact position of the motor the best solution can be some up-thrust or some down-thrust: Up-thrust if the plane has a tail in the prop wash and the motor is not too far back. Down-thrust if the motor is not too close to the CG and/or the plane has no tail. If there is no tail and the motor is mounted high above the CG it will probably never fly very well. flitetest.com/articles/Motor_angles_for_pusher_planes
I would mount it on top with some thin plywood glued on both sides of the foams outside, perhaps bigger than the motor mount and then predrill small holes to screw through the wing and plywood, With the aim to be able to bend the motormount to the right thrust angle, witch i would try first to see if it was possible
