I try to carry mine. Not often, but it did cut a few arguments short for me when my business stays were booked for me by a third party and may or may not have been on Priceline. OK, you can't go home and get it. Another possible solution, primitive as it may be, is to print out your account header and hand them paper. So last millenmium I know, but it works. Kind of like last month when the label printer broke. The place froze till somebody remembered we had an old IBM Selectric in the closet. Two of us could actually remember how to turn it on and hand align envelopes.