My sister lost or had her purse stolen while traveling (post 9/11) a few years back while traveling. She went to a local Sam's Club in the area, who of course had her photo and info on file. She had them print another card, and apparently that sufficed. Don't know if she got the SSSS, but even if she did, that's not terrible.

I always check for my wallet w/ my DL when traveling before I leave the house. I also have my passport in my regular carryon just in case.