I'd recommend a lamination and mount to 1/2" gatorboard. My preference is a cold laminate combined with a thermal mount. I've been mounting 8' panoramas with a cold lam/cold mount to gator for 20 years, and prints that have been hanging still look good.
(I will say that the original prints were made on photographic material, with a horizontal enlarger, and they are not nearly as nice as new prints made on inkjet printers from high res scans)