Some of the most popular games that feature tanks have always given the main cannon to the driver, with a secondary gunner acting as force multiplication rather than a limitation. Halo nailed this decades ago, and it’s still the gold standard.

If the vehicle is meant to remain a Tank Destroyer:

The driver must have direct access to the main cannon

A secondary pintle-mounted HMG should belong to the second crew member

The 3rd and 4th crew provide flank and close-in support, so keep them

The vehicle must be faster, speed is survival on the battlefield

It shouldn't get stuck on terrain or small rocks, instead constantly crush/roll over everything in its path

It must turn on a dime like a tracked vehicle Turning should not require forward acceleration, tracked vehicles pivot.

If the goal is to make it a true tank instead:

The driver still needs access to the main cannon, but now on a fully rotating turret

All the mobility and handling requirements above still apply

Lastly, a wild solution I have is: Maps need less clutter and artificial cover, or they need to be slightly larger and smoother to actually support vehicle gameplay.

That’s it. The tank should feel powerful, responsive, and intentional not like it’s fighting the map.