soffit mounting for Klein and hummel 0300

Hi everyone, It's my first post...Awesome forum by the way!!! Do you have any recommendation about mounting my Klein and hummel 0300??? I found a lot of info but never about the k+h. My room is 16'1'' wide and 13'5'' deep. I have a cathedral roof(start at 8' and finish at 11'). Here a old picture with the genelec, but give you a good idea of the room.... Here a really bad example of my new set-up.. I want to make a new wall on the 16'1'' wall. Give me your recommendation...Thank you everyone and sorry for my bad english... yannick