Dave, your idea of using a Y-harness cable is not only a good one; but it mimics reality, too. I've read that German halftracks used a steering system whereby when the front wheels turned more than fifteen degrees, the braking system would start to act on the track on the side of the turn. And, that this was the reason that German halftracks didn't need a powered front axle to help "pull" the vehicle through the turn - unlike an American halftrack, which did. Even the little Kettenkrad used this system, and there are photographs of it operating with the front wheel missing entirely, due to the steering system.

Great build! -Mike