If you want to rotate a page simply do this. Double-click on the item in Paperless to open the viewer/editor (this is different than "Edit document" which crops and does arbitrary rotates). Then you'll see toolbar buttons for rotating the entire document. To rotate just one page. click on the page's thumbnail then in the body of the page, right-click - a menu appears and you can rotate a single page as well as other options.
here is a screenshot: