before i left alberta, i bought a tansit plate, to which i was told was only valid in canada. i picked up my bike from Michigan, went to the michigan motor vehicle department and got a transit permit, to which i was told was only valid for usa. i mounted it on some cardboard, clear taped it, and mounted it like a license plate (as the bike didnt have a windshield). drove west across the states to idaho and north to sweet grass, zero problems across the states, crossed the boarder, cdn customs, never asked about the license plate, even thou he did come out and check the bike over. legally, i should have swapped the plates, but was to lazy, drove back to calgary with the usa transit plates.
again, zero problem.
hope this helps
ps, the transit plates for usa were us$10, and the cdn transit plates were something like cdn$30