Remote Ballista

You can use it while driving.

When you install them on your walker, they face backwards.

Press and fill The Remote Ballista with ammo (Flint Bolt, Flint Harpoon or Fire Bolt).

While driving, rotate your camera so you are looking behind you, and then if you have ammo in your inventory or in an ammo box, right click or left click your mouse button.

In testing, the ballistas will hit your Wings a lot (since they are firing backwards and most walks Wings are on back of ship. I suggest retracting your wings if you plan to use them consistently.