Not only is the 4WD function dependent on the ABS sensors, but so is the odometer, the tripmeter and the speedo.
The speedo governs several other important functions, most notably the cooling system (under 45km/h it will pull the air through faster).
In a word - you can't disable it.
My preference - and it's my driving style and what I'm used to - is to be able to steer. We had some exciting fun in a state forest once when we saw some incoming weather, packed our things and started heading off - only to be confronted by a deluge on soft clay. Being a forest trail it was neither level nor straight - and locking the front wheels (when towing, no less) would have been utterly dangerous.
For me, on that sort of terrain, I just do it slow. 4LO for maximum traction and take my time with no risk to me, the other occupants or the vehicle.