
I will be taking a look at this for you
Our backing up when leaving rule takes into account:
1) Vehicle in Reverse Gear
2) For more than 1 meter
3) Current trip distance is less than 20 meters
As this conditions look like exactly what the driver would do when they would back up to attach a trailer I do not think there is a way to differentiate between the two situations
One suggestion I would do is to analyze what distance is the average it takes drivers to reverse into trucks and modify the distance they do travel in reverse and try to tweak the distances referred in the rule so it ignores the trailer hitching operations