The 3rd battle of Kharkov (Feb. - Mar. 1943) would be most appropriate for your vehicle. All three of the SS panzer divisions which participated in this battle were equipped with the panzer IV ausf. F2/G with the double baffle muzzle brake. I'm pretty sure the base coat was dark grey as the Dunkelgelb base color didn't start to be applied until that spring (1943) and you can see brand new Tiger Is from the same battle painted in overall dark grey (not whitewashed). Greatcoats would be appropriate for this battle although some of the grenadiers also had knee-length, fur-lined and hooded parkas that you can see in photos from this battle. I don't think it was possible for the Panzer IV driver to drive with his head sticking out of the hatch (unless he were a particularly tall fellow with very long arms and legs!) but I could be wrong.
(ref: The Battle of Kharkov, Restayn, J.J. Fedorowicz, 2000)