Vehicle meshes on that vehicle aren't ideal. If bots were to spawn all the way back then, crossing those narrow paths, the battle would actually start like 15 minutes into the game.
Devs decided it best to have them spawn at the front.
Its possible to fix, but requires some really careful vehicle meshes to make bots drive along them smoothly.
Can be done. Who knows. If you had a vehicle driven to the front tho. I think they will use the gun positions.