A curly red wig, a caftan, and some chunky accessories are all one needs to conjure the surprisingly beloved Helen Roper. — Last Saturday I participated in the inaugural Mrs. Roper Caftan Crawl in Dayton, Ohio. It was magical fun, for reasons that defy logic. After all Mrs. Roper, a minor character on a 70s sitcom, should have become a footnote in television sitcom history by now. Mrs. Helen Roper (portrayed by…