Got the caps done, 4-1/2" hole saw worked great, the right size with no trimming. On the stock "mag" wheels they need no further work of the type described by dieselengineer. I did fit one up when I had my spare on, just for giggles, and the cap did bottom on the end of the studs before seating on the lugnuts, so I would guess the thickness of the wheel on the bolt circle may affect hubcap seating. . . The studs are definitely longer.
One of the studs in my kit had the threads cut round, so the same thread met itself, ie no inclined plane, just annular. Wow was that hard to figure out, no way to screw the nut on, and no it wasn't left hand thread either! I've never seen this before, anywhere. Like a ring-shank nail...