The BenQ W1070 is a 16:9 projector, not a 2.35 projector. It's native aspect ratio is 1920x1080 and that's the resolution that you should be doing everything at. If you feed it one of the supported resolutions it supports, then you can work with it however you would like at that point, but you should be realistically be feeding it 1920x1080.
If you want 2.35, then the proper way to do that with this projector, is to take your 2.35 source, stretch it vertically to fill your screen, then use an anamorphic lens.