Don't I know it! He's such a fruity horse. Really he's camped all over at many many rides, and should be quite experienced with these things, but I swear when we have to pass campsites near the trailheads, with scary looking tents and tarps, his feet never touch the ground, he's wound so tight.
You know, what you might want to do is tie a blue tarp up in his stall so that he has to stand by it to eat. I know you'll have to force him in there at first, and go in there with him to boot, but he'll get used to it eventually. When I'm halter training my babies, I'll lay a tarp on the ground and sprinkle feed on it. Of course I weight the edges down with rocks and try not to do it on a windy day at first, but when they get used to it, they actually LOOK for tarps coz they know they're gonna get a treat.