Brakes would be the easiest option for steering regardless if modular drive train or a simpler solution is used. Many early tanks used clutch and brake for steering. Steering lever had two ranges, first half of the range disengages the clutch, in the mid position the clutch is completely disengaged and track speed have no influence on the engine. Second range engages brakes as just disconnecting clutch from the transmission is not enough for the steering. This way driver can halt tank really fast if needed and still keep engine running.
Tigers and Panthers had different steering system, as far as I know, they had multiple gearboxes. Main gearbox would connect engine to the rest of transmission and two other gearboxes connect sprockets to the transmission. I haven’t tried it yet but I think it’s possible to build this using modular drive train. Not too sure how to make actual controls for this setup as it requires pair of actions mapped for each track, like 4 buttons just for steering. Would be easier with gamepad.