Okay, he just did it again when left for 2 hours, 1-3 this afternoon (I'm home today due to the holiday; I'm a teacher - ordinarily, this would be a day where he's crated for 8 hours and some change. ). I took him for an hour-long walk at noon, where he both pooped and peed, then I came home, and crated him so that I could run some errands. Came back to a big puddle on one side of the newspapers I'd left on either side of his crate.
It's seriously not a physical issue, it's definitely behavioral. I'm getting a little worried that it's becoming established as a habit..."go in crate, pee." I could understand it if he went in at 8 a.m., and we were late getting home and he didn't get let out until 5 or later, that there might be an odd accident, here or there (although he's proven that he can hold it for that amount of time). He's an adult dog who is absolutely capable of holding his pee for two hours. I don't think it's about that, I think it's a reaction to being put in the crate and me leaving, no matter the amount of time. I think it would happen if I put him in and went out the door and stood on the porch for 10 minutes and came back in.
What to do? I've done everything that all resources recommend, as far as making the crate a pleasant place. I can't put bedding in it because he'll shred it, but I stock it with his favorite toys and hide treats in his Kongs, I leave it open as a nice place to go lie at will (though he seldom does), I feed and water him in it so he associates it with food, I put him in it for short periods of time when we're home so that he doesn't always associate "crate" with "people are leaving." I don't know what more I can do to make him more amenable to the crate, but I have no choice but to use it, due to his behavior.