I agree with Ken, but you could also rough up the outer surface of your piece of T Track with some 80 grit paper, and then epoxy it into the slot, or you could use flat head bolts and nuts on the back side instead of the wood screws to attach it.
Making a dual purpose jig is a great idea, and it reduces the jig storage space needed, if you save your jigs like I do. I hang mine from my shop ceiling when they are awaiting their next use, and I'm running out of ceiling space.
I usually use my Delta Tenon Jig for this, because I can make finer position adjustments with it than I usually can when adjusting my fence. It will accept work at 45 deg angle too, although the stops for holding the work in position on it are smaller. For larger work I would most likely make a jig much like your's, but haven't needed to, yet.
Central North Carolina