OEM panniers usually not wider than handle bar. So used it as a gauge. After market varies since they produced 1 size fit all concept

That e class might not hear you. As much as I agree loud exhaust saved live, modern car bangsawan level has a good noise cabin insulation. So I usually cilok to the other side because one side close is one other side open.

Mind to share what brand. Is it effective.

That is why you see big bike almost always reverse parked or against a slope. With little push the gravity will help the bike roll down. And the most important thing, no need to pull back your heavy bike out of parking.