heres a few tips ive taken out of the book:

like dustin said keep the monitors 1ft away from walls.

keep your monitors as far as possible from the corners and side walls.

set them up along the longest wall because this will reduce both the intensity of any reflections reaching the listener and the extent to which the direct sound is compromised by the reflected sound.

so by the sound of things, it seems the most logical place for the monitors would be directly infront of the chimney (1ft away of course) purchase some thick curtains for the window, or even make a wooden shutter. some acoustic tiles for the empty wall, and bob should be your uncle. well thats my theory anyway.

i got the edit option on this post for some reason. so i used it, after i misread the diagram. ha ha

get that book though mark.