We could definitely do with a combat engineer. I've lost count of the times my friends and I had to hike it to the objective in ARMA III 'cause we drove our APC into an indestructible fence and lost our wheels.

He could also take some of the burden for AT fire, so Mischief can fully focus on being anti-structural with the capability for AT. (In the form of a 2:1 rocket load out in terms of bunker-busting to anti-armour)