@littleriverphil & danstamps: how do you handle mounting a cover where there are markings (backstamps) or stamps on the back? Or do you just make a note with the cover?
I have a couple covers with address, registration etiquette and other info on the front; but all the stamps are on the back. I have a couple more covers with stamps on both sides. I've tried using a "flippable" clear mount attached to the page on top or on the side. But such isn't real satisfactory and I'm not sure if these are suitable for philatelic archiving.
I follow Geoff's suggestion to place a back card between pages with clear mounts. I do use black, split-back, Showguard mounts for covers with nothing on the reverse.