Well, got some 2 x 4 looks like I can move the door over another 18" . I think I can then get a speaker 24" off the side walls. puts it closer to the 150 deg.
That gives me 95" between the two rear speakers.

Actually that is perfect. Puts the rears in line with the front which I just measured 24" off the side walls and 95" between

Anthem MRX520
M5HPv4
VP160HPv4
QS10v4