You smell like one, though
I just looked carefully at the cigarette lighter cord that I use for my 60CSx. As far as I can tell, there is no stepdown circuit in either end of the cord, so the GPS is seeing the entire 12 volts supplied from the vehicle.
So I would think that the cord from your Rino should work fine.
Your right. I do smell tadpole like. Can you do me a favor Lil devil. Throw a meter on your adapter and tell me if it is indeed 12 volts at the business end of the cord..You sound like you would own a meter or 2.