A paper matte will sag and buckle without glazing such as glass or plex.
Assuming you have the print well protected with some kind of coating and good mounting, one option is to use what are called "liners." Those are basically wood frames about 3/8" to 1/2" deep, with a bevel, covered with some sort of textured fabric. They're rigid, so no buckling or sagging.
You can be just like Peter Lik! Although unlike this picture he usually uses a $19/ft moudling from Roma called "Tabacchino." It's really ugly! It gives him a 4" moulding, with a 4" liner. That means 16" of each dimension on the finished piece is framing stuff, rather than image. The moulding in the picture in another (probably) Roma moulding that is a little nicer, IMHO. When I was following that stuff, Lik usually presented the print face-mounted on plex, which is fitted into the rabbet grooves on the liner.
More common liner sizes are 1.25 to 2 inches wide, covered with white linen, although liners up to 5" wide are readily available. Very handsome presentation, actually. Makes an 8 ply paper matte look positively wimpy by comparison.
edit...I stopped using liners with my canvases because a lot of customers felt that looked "old fashioned." They mostly prefer the look of a simple frame surrounding the print. I usually use the widest possible frame that will work with the print. Canvas somehow "forgives" such presentations, not sure you could get away with that with smooth paper prints.
