I am sorry, but I do not like this idea very much.
The game as it is can become quite campy, where both teams just sit on their side of the hill waiting for the other team to make the first move or some individuals rushing and quickly dying.
Giving them another reason to camp their bases (the defensive turrets are there ae well) would just motivate more people to stay stationary and shoot down vtols and aeros without actually entering the battlefield.
And besides, the mechs are of different heights, thus it would probalby not be possible to get a good solution. And as the weapon mounts are also at different positions, the opening would still be large, not providing that much cover.