one possibility is to use the ABV brake on only one axle and use...

one possibility is to use the ABV brake on only one axle and use it as the first brake to come on in a progressive braking system that still employs standard brakes on the rest of a road train axles .

That way the the ABV brake would take on a greater % of the total road train braking for when light braking occurs and the wear would be disproportionatly lower overall and therefore the payback on the ABS brake would be faster.
Maybe if it was the first brake to come on in a progressive system and installed on the last axle of a road train the driver could then also use it to prevent fish tailing.