What makes Kodak HIE fog more easily than other films is a combination of high sensitivity and clear base. The clear base makes the protruding end of the film act like an optic fiber, piping light in and fogging the film even all the way to the core.
Other films with clear base also fog easily for the same reason, but since the sensitivity is lower they don't tend to fog quit eas badly from a few seconds in daylight.
..perhaps one more thing to add: Kodak HIE has no anti halo layer (hence the halo's around bright objects against a dark sky), whereas other films with a clear base (TechPan) AFAIK do have a AH layer..
Ole, we did some testing a few years back and found that some felt traps on cartridges did in fact reflect IR and some absorb. IIRC one gent was able to eliminate his IR fogging substantially with the right kind of felt traps.
I fully agree with you on the clear base and would suggest that one keeps the film leader out of the light due to the light piping.