I have a problem, maybe it is only my feeling: the copperlist is in overscan, but the main game area is only 320 pixels wide. So if the platworm is next to left or right area border, player is not able to jump to the side, although copper creates an illusion that there is still enough space.
The overscan copper effect is nice and I like it, but I am not sure if it doesnt confuse player much. Maybe 1px wide black vertical lines where I drawn those red ones would solve it? Or it is not necessary? What do you think?