that is a clever idea, but if the combine is broken, you can't run it and the wrench to fix it at the same time, you would also need a lot of hose to get around to the back side, and, as far as I know, the thresher and header have to be on for the reel hydraulics to work, at least on JD I have used, maybe a guy could plumb lines to the front and back of the combine and hook them up so the combine engine just has to be running, not the whole machine