I like this style for a camp-shoe.
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I found a knock-off at Sam's Club for $20. Warm/comfortable around camp and waterproof enough that you can fetch water/step in puddle and they won't get wet. With a warm pair of Merino wool socks, in cool weather there great. Sole gives better than average traction. I wear Teva water shoes with Brookie Knee highs for paddling/portaging. The slip ons would do on dry trails, but if you really want a serious back-up pair of shoes, Mad_Mat's choice of footwear or the Teva brand would be hard to beat. Teva's Spider sole technology is amazing on slippery surfaces. I'm guessing any name brand water shoe would prove the same.

Knowing where you plan on going, I think a closed toe/heel shoe would serve you better as a back-up shoe. Any opened toed shoe/sandal or with exposed strapping is a potential snag spot. A badly hurt foot for a solo traveler would be more than a inconvenience :'(

For what it's worth, STP is a great source for items at a deep discount price. Their a Christian business that really does hold to their values.
I bought a pair of shoes that were way to small due to a mix up on their part in labeling. I called and they said send them back no problem. A day later they 2nd day air mailed me the correct size before I even mailed the other pair back!! You can't beat that.