You can use the fabrics for bags and backing. For the bags you won't need as much stiffening (if any at all). You would not even have to line the canvas bags if you finish the seams real well (I would use French seams if I did not line the bags) . You will need to use a bigger needle with a very sharp point (I would use a jeans needle -- probably a 14). Some of those fabrics ravel a lot, so I would stay stitch around the pieces -- a lot of starch might help.