We're flying essentially the same plane, and we've even had instructors unintentionally eject on the ground. Our solution is that non-rated personnel in the aircraft (except students) will leave the seat pin installed to avoid the risk of unintentional ejection. Pulling the front handle will send the back seat out first, so they just rely on the instructor pilot to do the ejection handle pulling bit. If the person getting the ride ever needs to pull the handle (IP dies suddenly inflight?), all they have to do is pull the pin out, drop it on the floor, and then pull the handle.
We have a ballistic 'chute in our plane, and we have always been paranoid that someone taking a ride will think to themselves "I wonder what happens if I pull this..." or if someone uses the handle to hold on... our solution? Same thing! That pin has been removed once a week since 2007 to prevent it from freezing in place, but when we are in the air, even if I am flying solo, I leave it in. Once, when flying in a VERY high traffic, high risk area I removed the pin in flight "just in case" but if I'm not expecting problems, I leave the thing in.
