I think you should follow what Dolby recommends as that's what likely designed/recorded against in the game/movie studios.
Surround Sound Speaker SetupI have no idea were you got two feet above ear height, ever since 5.1 came about, decades ago, its always been recommended about ear height.
If you will put it in non-standard location, route your sound through a receiver that has an auto-tune w/microphone feature. Made huge difference for movies for us. Most setups arent exactly perfect(walls, furniture and speaker placement). Also, the receiver learns the characteristics of your specific speakers. Never get another receiver without that feature after seeing it in action in living room. FYI, non-optimal, both rear are on ground and one is even behind couch because door... After auto-tune, everything sounds just fine in action movies. Good speakers/bad living room.
Ive never looked into it, but if you can get some sort of auto-tune software for your PC once your speakers are setup (you place microphone where your head would be) and save that sound profile.. Maybe that's why folks get sound cards still.