well presumming you'll put the speakers on the wall with the window, the fact you've got a odd stud wall coming out at the back is great i would have thought cause it'll bounce the bass energy off in all sorts of directions and get rid of alot of it. also the window sounds good cause then alot of your bass energy will bugger off through the window and not be reflected back. i would work on a huge bass box at the back though (use that link i sent you to construct it) and definitely bass traps (you can order these like i did or if you're on a budget, that article tells you how to make these too)
good luck man!!!