I dry-press mounted an extra layer of mat board (slightly smaller than the print) to the colored back mat. I then dry press mounted the artwork onto the hidden mat. In order to prevent the edges of the smaller hidden mat from embossing themselves onto the print I put other pieces of mat board around the small mat so it was larger than the image while pressing it.
I wouldn't do only a single edge. You can either buy paper that is the right size for your image or you can use something like the Dual Edge Ripper to tear your own paper. There's also the old "fold the edges, wet them, keep folding them back and forth, then tear them" method.
I don't like having a straight image edge on deckle paper, so I only print things that have a pure white edge color (naturally or by adding some sort of natural looking white edge to the image).
