Firstly, I agree with your assessment that a rear ported speaker will not work. Although I do not mount my speakers on a wall, I have to place them close to the rear wall and I have found rear ported speakers do not do well in those circumstances.
Vienna Acoustics has just come out with a wall mount speaker that you may want to investigate.
I have seen and heard LS3/5A's mounted on a wall, and although not ideal, they seem to sound fine. I have Spendor S3/5's placed close to a rear wall (on stands) with little ill effect. You will need some hefty brackets to mount them on the wall.
Vienna Acoustics has just come out with a wall mount speaker that you may want to investigate.
I have seen and heard LS3/5A's mounted on a wall, and although not ideal, they seem to sound fine. I have Spendor S3/5's placed close to a rear wall (on stands) with little ill effect. You will need some hefty brackets to mount them on the wall.