Another vote for the plak mounting for panos.
If that's a bit too tacky, then you could print a "matte-like" border, leave some white space on the print as a substitute for the matte, then have the print dry mounted to either foam core or gator board, frame with no glass.
That's wat I do with my display prints up to 17x25 which frame out to 24x32 - I use acid free foam core wich gives a 3.5" surround, plus a spray of PrintGuard. Very light and over the past couple of years no problem with warping since the frame basically holds it in shape. Only downside is they are a bit fragile to transport - I put 2 face to face and use masking tape on the edges. I have them professionally dry mounted to foam core I supply and the older ones are over 3 yrs with no separation or any other problem. In addition to being significantly cheaper than matte and glass, there is an added benefit of no issue with glass reflection. Nonreflective glass is really pricey.