An oblong hole will not hurt, put CA in to stiffen the wood.
I like airplanes that put a ply block in the ailerons, where all you need to do is drill through the block and install screws into the block iself. no need to drill all the way through and no need for a backing plate. Seems like such a simple thing to do during construction and would be an easier assembly for the beginners I don't know why manufacturers don't incorporate this into trainers.