Another vote for a lightweight 22. A ruger SP101 8 shot 4.2" would fit the bill, as would a Ruger LCR in 22.
I had both. Sold the SP101 as it didn't get carried. The LCR I've used as a dispatch tool on the winter trapline, and it'll be good snake medicine while kayaking (loaded with shotshell 22's).
The LCR is feather light and since it's polymer, I don't really care that much to get it dirty or potentially wet. Accuracy is about what you'd expect from a snubby double action revolver - coke can at 10 yards if I concentrate. Certainly minute of snake at 6 feet.
