I saw a show here at HCP last summer by Lyle Gomes, who shoots 4x5 with a mask on the groundglass and uses a cut-out darkslide that turns it into a panoramic negative of 2x5. He enlarges these on conventional enlarging paper and achieves some very good results. Of course, this is not nearly as fun as hauling around a 7x17, but might be more sane in practice.