Sorry but this assumption is just wrong.
Although it was not named Salic Law, in the HRE, and then in the German Confederacy that succeeded it in 1814, all the kingdom and electoral principalities had basically the same succession laws as France. Which is that when a king or prince has no male offspring, then his closest male relative on the older younger branch succeeds him even if he had daughters.
This is why, by exception, emperor Charles VI had to devise the pragmatic sanction for his elder daughter Maria Theresa could retain the Habsburg ancestral kingdom of Bohemia and other principalities.
This is why lateral male branches of the Wittelsbach succeeded to the elder branch in Rhine Palatinate and in Bavaria.
This is why Victoria of Great Britain did not become also queen of Hanover.
You give a nice overview, but this was not so much a rule in all the German lands (and not all the French lands, e.g. Flanders). I think the more reasonable answer, at least before ~1500, is that it was all a mess and the big question was what you could enforce. Younger brothers and cousins tended to be firmly inside the local power structure and thus had a leg up over daughters and sisters who were usually shuffled off to be in the power structure of their husband's court. An underage son would usually short-circuit this issue because it was too traditional not to have him inherit... and obviously many sisters/daughters and their husbands DID press their claims, sometimes succesfully (see e.g. Jacoba von Wittelsbach in Holland-Zeeland-Hainaut).
And in all cases, I think it was firmly established that a lack of any male heir would lead to (through-)female succession.