It would be an option to use a different field, but I've learned the hard way that this is a recipe for disaster.
Besides if there is a suitable and supported field, why not use it?
I have written a small program in Perl, but it would be so usefull to have it directly in PM.
Usage:
1. My clients do not need to know my internal filenaming
2. By using simplified names for clients, I solved the problem of mistakes in ordering.
Cheers,
Boris.