best porta potty enclosure

My problem. The Dog has separation issues when I head for the campground restroom. Not a problem when using the shower, I just put him in the crate in the truck. This works for cold weather camping like spring trout season. In hot weather I'd have to lock him in with the air on, but that would work. But just a quick trip to the restroom when I really don't want to cage him, turns him into a nuisance barker. I was thinking that an enclosure so some sort, maybe a shower type tent might work. Due to wind, it would have to be staked down. What do some of you use and recommend?
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