That actually is a way better idea.
I assume everyone noticed by now that I am against the complete non-existance of clipping. What
@Valiant70 suggested is how it should definitely be, as we then get the best of both ideas.
One more thing: the turret barrel should have a set range at which it can turn (which naturally is vertically), to avoid it clipping too far. I'm thinking inbetween -5 and -10 degrees and then 85 degrees (negative is down, positive is up). It's not 90 degrees because that would make turrets have no blind spot, which would be terrible for gameplay.