It really isn't all that bright. If your concerned about it, lose the cabinets and relocate your gear to another room. The JVC RS46 accomplishes 2.35 by lens shift and zooming, so bars are on both sides. The only solution to zero off screen projection (even though they are a dark dark black) would be to use an anamorphic lens or stick to 16x9.
I heard that the anamorphic lenses are expensive and that you have to get some motor to move it but it sounds like it would solve my issue. I'll look into the JVC also. I think that my issue really is screen size. My front row where I want to sit for best sound is only about 10.5 feet back while my back row is better at 16.5 feet back. I currently have an old 720p epson and a sheet that I am playing with and I set the projector to display a 126" diagonal 16:9 picture which feels a little big for 16:9 content but seems fine for 2.35 content because it isn't so tall. I thought if I switched to a bigger 2.35 screen it would still be great for movies and the 16:9 content would be a little shorter that what I have it set to now so it would be better also. Plus I think I have kind of a hangup about how when you watch TV it is small and when you go to the movies it is big. A 2.35 screen would make the 16:9 content smaller and the 2.35 bigger since it would be fixed height.