I wouldn't get fancy. If it was just stereo listening I'd say put the speakers on the east wall, but for HT the screen has to go between the speakers, so the north wall is more or less your only option. The acoustics are going to be strange in that space, and no amount of trapping is going to even it out, so I think I'd just go with a few traps behind the speakers, a big subwoofer, and enjoy the rumble. Put the speakers near to you ("nearfield listening") so you can play them softer - both for the sake of the neighbors, and to minimise the room's effect on the acoustics. Try to put the seating as far from the back wall as you can stand it, as right against the back wall you'll get an annoying bass boost.