Hard to answer- it depends how good a job you do cutting it so that it fits tightly on the spool. If it's cut much too short then there could be a lot of fogging from the edges. And some films are notorious for light-piping all the way through, e.g. HIE and any IR or extended red film will probably give problems and the loading and unloading should be done in the dark. I vaguely recall that some of the film bases really pipe like crazy. To be on the safe side, it's probably best to load and unload in the dark and use a black container for the film.

The slit film I bought from somewhere came wrapped in foil! I would definitely store it that way and load/unload in a changing bag or under a jacket or something.