How do I sand stamps off of lumber?
If you can get under your deck I'd try and do a test sanding just using sandpaper and some arm strength to see how easy the stamps come off. I'd be willing to bet a small orbital sander would do the trick with some fine grit paper.

Orbital sanders are pretty cheap so convincing the wife shouldn't be too much trouble. Maybe hop on craigslist or ebay and see if ya snag one on the cheap.