I Think this Could be an Solution.
Or what also can work is to have the posibility of to set active filters by the player at the grand campaign.
This gives the player the pisbility to regulte the place where he want to fight if he took the proper wheapons for that scenario.
I think the publisher shouldn´t forgett that some players paid real money for an campaign pack like Stalingrad, because they wanted to play this szenario prefered to others.