Thanks for the ideas. It didn't occur to me to move the image. Also, now that you mention it, top and bottom is an issue, especially top.
I am using a single Projection Design DVision 30 XC. Horizontal lens shift went out, thankfully it was centered at the time, but motorized vertical is still working. I get 14fl with brilliant color on, but a grayscale ramp has banding and very light pinks and green color tones. Sports and action movies it is not an issue. Movies with snow and white shadows can get a bit distracting, too me at least. Without BC the grayscale ramp is perfect but the image is a bit dim. I have a second one of these projectors and was thinking of possibly stacking them. Screen is DIY AT Centerstage XD. Speakers are in the the upper 2/3rds so shifting the image down might be an issue. Also, the top of the screen is about 14' in the air and climbing up on scaffolding to put on the masking is a no go. I totally didn't think of that.
How about moving the image up to the top and hanging the velvet from the bottom of the image. Will the thickness of the 2x3 at that bottom of the image, top of the mask, be a distraction? I was thinking of using magnets to mount the mask so that slight adjustments could be made. Yes/No? The ones I have are rare earth and hold 10+ pounds.
Again, thanks for the help and saving me from trying something dumb.