I think the ceiling mounted surrounds is a good idea, but if you're unable to do this, I might recommend an irregularly spaced placement on the walls running from the corner where the bed is. For example, halfway down the wall running parallel to the length of the bed, and maybe 1/3 of the way down the wall running parallel with the headboard. Just a thought - but best to use some experimentation to see what sounds best.
The fronts should be less problematic, if you can keep them clustered at some equal distance from the TV on either side, and above or below for the center channel.
That's a challenging room, as corner placements often are, but best of luck!
