However, one can argue that a coated print glued to Gator is hermetically sealed by the coating on the front, and by the dried glue on the back. In the absence of solvents such as water, pH is a rather moot point and very little chemistry can occur. In support, I have examples of prints glued to Masonite umpteen years ago which are still in good shape.
Compare that to the standard archival package where the print is under an acid-free matte and behind glass. Each day as the temperature rises and falls, the materials expand and contract in a pump like fashion, pumping in a newly contaminated air sample each day. Humidity, respiration products, smog, etc.
My theory is this...hermetically sealed prints with what amount to dried barriers front and back are likely to be more stable than acid free packages where the internal air is re-charged with fresh crud every day.
But in regards to labels, for 2.5" and wider moulding you can stick Avery #5263 labels right on the moulding. Sometimes I also attach larger write ups printed on light cardstock to the back of the Gator with blue 3M low-residue tape. On the tape I mark "remove" and even though clients rarely do so, my fanny is nevertheless covered. Note that Lowes and HD now carry other brands of blue tape that are anything but low residue, use only the 3M version which can be neatly removed from Gator for at least several years.