I have had much confusion about typeglob games in the past because I missed the simple fact that when Perl sees Foo::Bar it resolves what that will mean at compile time. Therefore rewriting what that should be at any other time is not going to cut it.

Try rewriting the contents of the typeglob in a BEGIN block and see if that makes a difference. If you run into trouble, do lots of thinking about what things look like during compilation, and what they look like at runtime. (Keeping in mind how loading other things might overwrite stuff, and what operations happen when.)

Good luck!