Sadly, that kind of flare comes with uncoated lenses. I learned that in 1981 trying to make a back-lit photo with a 12"/4.5 Velostigmat, also uncoated. (That's a Tessar design.) Don't know how you'll get around it; it seems that small wide-angle lenses for 8x10 are few, and coated ones are fewer. Perhaps a 190mm Kodak Wide Field Ektar; it should cover whole plate. They're not exactly common, though.