Yes, this would be a great option to have. I run linux so my solution is easy (change the permissions on the dir to 000, then change them back) but when I was using TDT way back when, I suggested this to the author and it got added eventually. So Rockbox should get an option for doing this (no software used with the retail firmware should best Rockbox in *any* way!
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The --strip option just strips off some part of the file path off the front. Say, "--strip /home" and your /home/music/file/path becomes /music/file/path in the database. I think.