Agreed, there are a bunch of hacks. My minivan is getting redone after my last guy f'ed everything up. So I went to the best guy in the area and he is going it right from the beginning.
So a simple plan would be:
(1) If MB offers a Blu-Ray in another model, it may be possible to transplant that system into your car and keep everything OEM - maybe the dealer will do it for you.
(2) If there isn't an OEM transplant solution, I'd just call the best shop in your region and...