I'm pretty sure that any signwriting on a vehicle would be obliterated BEFORE it was sent to auction.
And as an aside "Copperhead" chimes nicely with the "Copper" (although it wasn't always made of that metal, especially when the brew was illict), or boiler, used for heating the mash to boil off the alcohol. The fiddling Doherty brothers were itinerant coppersmiths, who repaired "utensils" on Irish farms.