Marders covered almost all approach routes (except the very one I took with my main tank assault after due scouting), 5cm and 7.5cm fixed PaK was placed between buildings so as to be covered from the front but to have clean field of fie parallel to the frontline - of my lost tanks, about 1/3 went to these flanking buggers
Fortunately my air recon didn't find them and they were far enough from my infantry screens to be discovered prior to opening fire, so I wasn't able to laugh at how the AI put them in places where they cannot hit anything that's coming at them from the front
As it was, I was able to smoke them, bypass them and the secondary attack infantry wiped them out during cleanup, but this took time and some blood.