We use these:
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They are e-zip brand and that particular one is a 750 watt scooter. You can find them fairly cheap ($100 - $200) On Craigslist. New I think they are $299 at Academy Sports. You can also find the same thing made by Scwinn, I just can't remember what they called them. I have one of those as well in a 350 watt that does just fine.
These actually ride in the 5er with no issues.
Obviously you aren't going to hop on it and run into town for something. But you can't beat them at the campground to get around on.