trash the tire. One very expensive tire is a whole lot better than an hour on the side of road changing a tire, two weeks at a body shop repairing body panel's, a lifetime of the wife bashing you for being too cheap to replace the tire. Just my experience... been there done that... Trailer tires take a lot of abuse, the sidewalls go through alot of flexing and heat buildup, I really don't think a patch or plug would hold up under that preasure...