So Harley is going to sue for ordering a banner from me
Are you Harley-Davidson authorized? By the corporation, not the dealer?
Did you go through the application paperwork, the submission of products, the wait for approval to sell specific items?
If you didn't, then Harley can and will sue you, the dealers are supposed to buy from authorized merchants.
The newspaper ads come from authorized artwork given to the dealers in their media packets. There are also authorized design companies around the country that do custom advertising for submission to newspapers, yellow pages, billboards, radio, etc...
I've been down this road the legitimate way.