How to make AI work for a ordinary Pawn?

I am trying to make some AI controlled tanks with Nav Mesh Bound Volume, AI Controller, Blackboard and BehaviourTree. I have experiemented several classes and found that only DefaultPawn and Character classes would be able to navigate correctly. Others like Pawn or VehiclePawn would not move at all. For DefaultPawn it moves like shifting, i.e. without turning to the direction of moving. So that leaves Character class the only one I know that would behave correctly. Yet the default settings in a Character class (capsule collision, skeletal mesh, etc) are not very desirable for a tank. So is there any other way to make AI work for a ordinary Pawn?