Well first off, if the couch will be against the back wall, I would only use a 5ch bed layer. IMO, you should have at least 4’ and maybe even 5’ behind you for 7ch. That also holds true for any layout with 4 overhead speakers. Including 5.1.4 and 7.1.4. Rear top/height should be around 45° behind the LP. Can’t do that with the couch on the back wall.
FWIW, I used RSL c34e for my Top speakers. They image like crazy and blend very nicely with my bed layer, despite having a soft dome tweeter vs titanium in the bed layer. My side surrounds are also in wall. JBL studio 2 55IW. They’re not as good as the in room monitors that used to be there, but they are very good.
All things considered between MLP on the back wall, and small dimensions, I think 5.x.2 will be best. If you try to use 7ch bed, the rear surrounds will be distracting as they’ll be too close, and you won’t get good separation between them. They also won’t image very well. Same for overhead speakers. They should be placed like this.
You can see, the overhead speakers basically form a square over the MLP.