None of your options are appropriate honestly.
All I see here is you failing to find a solution and then considering you want to change equipment. Make it significantly worse for yourself.
You're getting a **** ton of bad information here.
First things first. Straight couch only. Sit away from walls. Bookshelf speakers for fronts and surrounds.
Don't listen to anyone that says ceiling for surrounds. This is downright disrespectful for home theater and I consider it a serious...
5.1 has surrounds not rears.
Back wall sounds like the wrong placement. Show me a floor plan.
Ceiling is for Dolby atmos and dts x and under no circumstances do they ever get used for any ear level speakers.
Answer to question is surrounds go into surrounds/sides terminal.
Ceiling speakers...