Driving a tank without a gunner feels horrific in this game
The turret turns too slow to react to any infantry nearby, so you rely on your gunner for those situations. It has never felt worse to be missing a gunner than in this game, you have to play extremely defensively without one.
On top of that, the MBT's mine detection only works if you have a gunner, so you have to drive way slower without one as well.
Maybe make tanks/IFVs pulse on the map on the spawn screen if they're missing a gunner, add some bonus points for spawning in the gunner position, something, currently it feels so so so bad to not have one. I actively avoid using vehicles if my friends aren't online it feels so bad. Alternatively you could up the MBT turret turn speed to a reasonable level, or at least buff Optimized Handling so it does something meaningful.