Here you can see the result of the idea. To mount the backplate to the TV I used four M6x50 screws with some nuts and shims to fix the plate as you can see in the following picture:
On the backplate, I drill some holes which I used to mount the electronic devices with cable ties. This is a quite simple and easy solution but the result is astounding:
Everything is cleanly mounted on the backside of the TV. Further ideas could be to LED strips to the backplate to get additional illumination or light effects. The second idea could be achieved with open source projects like Boblight which could illuminate the background with colors matching the TV screen colors.