The Pak 40 and Pak 35 would have been seen in an early towed TD unit. A platoon would have the Pak 35s and the 2nd platoon would have the Pak 40s. Other platoons would have Pak 38 and ammo. This would be the make up in 1942.
The Pak 40 first saw combat in Russia. It was designed to replace the Pak 35 witch did horribly against the French Armor.
Markings would be any towed TD unit. And all 3 guns would be painted in German Gray as would the Krupp.
So, I would go with an Early war Eastern front dio.