It's been 70 minutes, so I checked the turkey. 105 degrees at the best spot. Potatoes weren't tender yet, either. So, it's taking longer than I had thought. Still, that's why we're doing this, to find out just how long it takes to cook this way.
But, personally, I thought that at 450 degrees, we'd have everything reduced to a char by now.
Update: removed the foil cap; perhaps roasting in an open pan will move this along.