I have a few friends who live in Germany and are in the VHS scene, 'The Mail Pilot' redrawn is available in a Felix the Cat (Felix der Kater) VHS collection, and they'll be on the lookout for it.
Though two questions, how can we be sure 'Double Performance' is Grampus and Scrappy? And while there's seemingly no evidence of a Scoots Through Scotland redrawn existing, I wouldn't fully count it out, Tommy Stathes made a post a few years ago saying he most likely has the short on VHS, presumably one of those compilation tapes. In the latter's case we just have to wait until he has enough time to fetch it from storage.