Being a low wing plane, I would not leave the switch on that side. Especially with a 40 sized two stroke. That switch will be full of oil after a couple of flying sessions. You need to move something.
Solution number one--take the switch out, and put it on the other side. Then, fill the hole left with some stock balsa, and cover over. No problem. Easy fix, and probably the best of the two suggestions that I have.
Solution number two--invert the engine. This would put the exhaust on the other side.