You can do it but it might look a bit funny. You would have to have the screens motorized frame mounted under your bulk head as a motorized 120" screen will be around 118" wide (frame case). The viewable area would be approximately 10" below the bulk head and around 14" off the floor. My screen is also close to the floor and it looks rather good to me but mine is centered. Yours would look a bit unbalanced but workable...IMHO. Who knows, maybe it'll look great!
As for the projector? I'm not that familiar with that projector, not too sure about the lens shift of the W1070. It might hang a little low if the lens shift is not great.
If you can work it out, I'd go for it. Projectors are awesome! nothing like watching a movie on a large screen.