Author, your idea is original! Your edges, however, need refining. The cut borders are too sharp. Selecting the elements, inverting the selection, expanding the edge by 1 pixel (or 2, depending on the resolution of the original), then modifying again using Feather set to 0.5 pixel, and THEN deleting/trimming the excess helps fix that problem. After final placement in the scene, running the blur tool set as a small, round, soft, low opacity along the edges will soften any ragged edges and blend into the scene even more. Good luck!