For what it is worth, my experience of the pockets is that they are too small and tight to hold anything except perhaps a cloth stuffed in the top. I have the Heritage catches and while they are better than the standard Dzus fasteners the springs can weaken over time - my bonnet now moves forward c.7-8mm.
If I recall, you have had TM advice on importing and registering an EU3 v EU4 in France. I would counsel against an EU4 with the EU3 'Appearance Pack' as your M3W would breach EU4 compliance - as Chris99 points out, resale (and French licensing/testing?) would be difficult.
