FWI I have never done the medial head, only the lateral, something instinctually is telling me that the medial head would be painful. IDK if it's true but I'm not interested in finding out. I had the same instinct about my quads and received confirmation the painful way.
As far as hard to reach, I am not flexible and I reach both sides easy, sitting in a chair or laying on my back, bent at hips and heels to ass. Not much coordination issue for the opposite hand , you can brace the heel of your palm against your quad for the insertion
