There's something called "not using roads" and "avoid the obvious paths"
[...]
But there is a way if you want it.
Also - minesweepers in transport vehicles detect mines. You can send one in just behind your tranks and no mine damage.
It's easy to make a theory work in your fantasy than in reality.
It kinda sucks if there are only 3 paths to the enemy's artillery unit and one of them goes through the frontline. It's incredible hard to stay unnoticed and the enemy will obviously take precautions (as mentioned mines, keeping the arty units close other units, instant retreat after firing, firing from maximum distance or behind shotblockers).
Trying to ambush the enemy behind his lines is a suicide mission. Losing a tank+light vehicle+pios is not worth it.