Looks like you have a great room if you utilize placement correctly. I'm far from being any kind of expert and I don't even have much installation experience, but after doing lots of research I'd say your plan is far from ideal as you have it.
1. The rear surrounds are too close to the MLP. Go with just dipole side surrounds or move up the MLP if possible. There should be >3 feet behind the seating for good rear surround placement.
2. As aesthetically pleasing as it may be to have the LCR up higher, the tweeters should be at ear level. If you don't want to move L and R down, then perhaps just put the center underneath the TV.
3. I'm familiar and partial toward Audyssey's DSX (as opposed to Dolby's) guide for heights and wides placement. The wides should be on the side wall, and at ear level, so I suppose you could try it but I trust the guys that do the research. The best place would be for the heights where you have the wides, and move the L and R out to improve separation.
Overall, I think this room was meant to have a 5.x system. A very difficult layout. There is a point when more speakers actually hurts the room. Looks like you could add front heights with great results.