It might be possible to move the screen a little forward of the window since it's over 19 feet long, can i ask what you value in picture quality, will you be calibrating the projector, do you like inky blacks or can you live with good blacks and good 3D, indeed is 3D important, do you want a projector that perhaps is good at most things, if it's the latter then i'd consider the Sony HW55 projector, a good all rounder. If 3D is extremely important then it's gotta be a DLP but you do sacrifice some black levels.
I dont know that I would ever use 3D. I dont know anything about calibrating a projector either. As far as blacks go, good is fine. I just want to make sure that fast moving pictures dont blur. I watch a lot of hockey, football and play some video games. I hope that helps and thanks for the assistance.