My wife did it, solo. We cached food at a few separate spots beforehand (with a backup nearby). We looked at bear vaults, but I ended up using 6" PVC and cemented the ends on. She used a little cable saw to get in. I also left an empty 4" tube with a screw-on end at each cache site, so she could drop off her trash. After she finished, we went back and collected the empties, the spares, and the trash tubes. 500 miles solo. She's a rockstar.

If you're gonna do it, pm me, and we can try to help with some lessons learned.