I think this is the most difficult room we have had. It is small, cluttered and with openings.
It will be a real challenge to get anything that sounds decent in that space. I can tell for sure adding more than two or three front speakers will downgrade sound and performance. In this case less is definitely more.
Speakers are going to be too close to boundaries. I think that room is crying out for a good 2.1 or 3.1 in wall solution at the TV.
These are some pictures of our great room system designed and built at my wife's request.
L-C-R are sealed designs. The sub is an aperiodic transmission line.
Now, one of your problems is the Baffle Step compensation issue, which handles speaker transition from half to full space radiator and is dependent on cabinet width. If a free standing speaker is placed close to a wall then the sound is muddy. So in wall designs are designed without BSC.
In my studio the main speakers are active except for the tweeter, and I have designed a variable BSC system so BSC can be optimized to location.
Our situations are not entirely comparable since that is a large space and yours is a small space. However, the situations are similar as there are few to no good options for speaker placement. So that design seemed my only option. It has been very successful and easily fills that large space and then some.
In closing I would say that the last thing your room needs is more clutter. So, you should look carefully at an in wall solution.