It's certainly a good idea. However, it might be worth starting with one of the better chrome bookmark extensions, since they already use the bookmarks API. I've recently found 'Neater Bookmarks' which is very nice. The only issue with it is that it assumes use of chrome's own add bookmark and folder features, so it a menu only and nothing else. The opera extension 'Add Bookmark' works well with it, but as yet it doesn't allow creating folders, so I have to show the bookmarks bar to be able to do that.
Another chrome extension 'Tidy Bookmarks' has all the functionality, but looks ugly to me. I tried to hack the html and css to make it prettier, but I wasn't ever happy with the results, and in the end I found a better looking one. I also stole the icons from 'Bookmarks Manager' (which has very nice icons IMO), for use with 'Neater Bookmarks'.
Hope that helps, and I look forward to your finished product!
