I've had problems with a rebate reflection in my negative carrier, which I've discovered is caused by the bottom sheet of glass.
Would a piece of acryllic of the same thickness and size, with a 6cm square hole for the negative, be an adequate replacement?

In particular I'm wondering about damage the acrylic might cause to the negatives (acid?), as well as potential flexing when the acrylic is warmed by the lamp and then cooled.