Sometimes I run (in reverse) film widths that are not 35mm or 120, namely Advantix (24mm wide), slit 120 (31mm wide), slit unperforated 35mm (17.5mm wide), slit 46mm (23mm wide). This is challenging but I do it occasionally.

But how to process lengths longer than a foot is challenging even more! Do you have any suggestions other than cutting down the center of a plastic reel so that the spirals come closer?!? I would like to know what thinking similar situations have resulted in. - David Lyga