Print a QR Code for SecureDrop in every issue of the newspaper. Hell, feature it as part of a story announcing SecureDrop the first time you print it. Then just

Print a QR Code for SecureDrop in every issue of the newspaper. Hell, feature it as part of a story announcing SecureDrop the first time you print it. Then just print it in a consistent position with minimal explanation from then on. This may be one of the rare cases where the use of a QR Code is justified.