Has anyone successfully used the 3-inch opening Packard shutter on the 6x6 2D lensboards? If so, can it be done without any modifications? I'm thinking no, since the 5.75 width is slightly wider than the (5.5-inch) recessed back part of the board. But it looks like there might just be enough slop to accommodate the extra 1/8 inch around each edge of the back of the board. Any advice would be appreciated