Seriously: look at the size of a bsuit, then look at the size of the humans.
Do you think the humans would be able to move very much, not to mention sprinting as fast as an unbattlesuited human and lasting longer at it?
There just has to be some hydraulics in the picture, which means the human would probably not need to have their arms in the arms of the bsuit, only have some controls.
And, i mean if there is a human in the bsuit, the only thing able to hurt that human would be hitting the actual human inside the armour, therefore, the hitbox should not be larger than the actual human.
And the bounding box works fine in game too, so there is no reason to possibly unbalance it by resizing the bbox because you think this is logical, but it is in fact not.
If you are going to be realism- freaks, reduce the size of the bsuit itself.
or make it so that the only thing any kind of damage outside the actual human bbox, but still inside the bsuit logical size, would only impair and decapitate the movement possibilities of the bsuit. this is probably what would happen in real life if we had battlesuits and fought aliens.
But now, trem is not real life, so i say you should leave it for the sake of not messing with allready eccelent gameplay.