I need to mount my rear surround speakers , running 7.1 here , onkyo 803 and polk's all around rti series

Back Room where should i put them on each end of the window same hight as my sides ?
or mount them on top of the window so i can get them closer togeather ? 4 feet apart ?

also if i mound them on top of window should i maybe have them lying down

if i put them on top off window its 3 feet higher then my middle speakers are

oother picks of my room can be seen here , picks

i know there back rears should be closer togeather but i jsut sure if thats to high or not would like to mount these soon as i get a responce , thanks