You could get an electric diverter valve and split the bucket cylinder circuit to run a 3rd function. Just need to run wires up the loader instead of hoses. Those valves aren't real high, would need a couple short hoses, couple tees, quick couplers, and a couple adapter fittings most likely.
I rigged a pair of them onto our JD 4430, it has a loader on it all year, joystick kit is expensive and complicated, and unhooking the loader to run an implement every time was a pain since the loader needed to stay up, can't disconnect under pressure. Now the loader stays connected permanently, flip a switch in the cab to go from the loader to SCVs.