Bleaching of any sort damages cell structure. Many bleaching agents also delignify wood (damages the connective tissue between cells). If you succeed in getting the visual results you want there is a good chance the surface of the fingerboard will be softer than it was when you started. This is a problen not just with increased wear but also with fret holding.
That having been said, A lot of the maple used in the industry for cheaper guitars has been bleached. A good finish penetrates the wood and replaces the lignin and fortifies the wood. This is done prior to cutting fret slots so fret holding is not so much of an issue.
Much of the color in rosewood is in the form of a variety of natural oils. It is likely that they will not respond equally to whatever bleaching agent you choose. These results are not predictable and may vary depending of the region of origin, not just the species.
Household chlorine bleach will not work for this application.
I don't recommend you do this.
