Considering you are asking about the rear end of the 5er, perhaps I can share my experience, considering I have a TT, but my trailer has a "rear" too. (why not?)
I have double opposing slides on my TT and the entertainment center is in the rear. However, the entertainment center does not go up the full length of wall, only half way, and the upper half is all window. This give full windows on all 3 sides of the living room area.
One thing we DID NOT like, and still do not like about the full wall entertainment centers is the fact it encloses the living room more. We preferred the windows and the surround view.... which is VERY nice by the way:
About the television:
We swapped positions of the couch and 2 chairs to provide more room and access when the slides are in. One thing we can do is move the chairs anywhere, and the couch. So we often turn the couch right in front of the television, or rotate the chairs. They are not fixed or anchored down, so can move anywhere. And nothing is obstructing the absolutely fabulous panorama through the windows all around.
Of course, there are also alternative ways to sit in the chairs too!
Here's our floor plan. If you did not know this was a TT, other than the lack of steps to the upper floor, you'd never be able tell if this is a 5er or a TT floor plan, as may 5ers have this (or very, very similar) floor plans. But for your purposes, just consider the back of the trailer. You may want to re-think having an enclosed wall. There are many models and types of 5er's with this same arrangement in the rear.
Why block your view by having the entertainment center all when you could have windows. The view outside is so much nicer than he view on television!