I have done bothe methods - circle template & airbrush w/ a Pzkpfw IV-D
and the Sharpie on my Panther.
my template problem was no template 'exactly' fit the rims.
(maybe i needed a metric template!)
w/ the sharpie, i had a few slips, but w/ so may roadwheels, and all the
overlap on the Panther, i should have no problem concealing them.
i guess no method is foolproof!
(i am speaking only of myself!)
ed.