Our current luggage does not obscure the centre brake light. In the days when we used a case that did obscure the light, I fitted an LED brake light to the case and created a Y shaped wiring harness that it plugged into. There is a connector near the centre brake light so you don't have have to make any changes to the wiring loom on the car.
Anything that makes the car safer is worth having in my view.
As an aside - whilst in the Alps, keep an eye out for banners displayed by professional photographers so that you can order their images - I have bought some super images over the years.
