How to seamlessly use “” for English and „“ for German on a Mac
Solution 1:
I'm not sure why you need US-PC for this.
Regular US [or UK too] have all the accents under dead keys - so the only thing you're gaining are the two 'enforced live' keys, which removes your ability to use those keys normally.
I can only show this with images of a UK ISO keyboard, on a US ANSI the key left of z migrates up to left of 1.
Standard dead keys, under Opt ⌥ 
'enforced live' keys [the dead keys are still present in this layout too]
In either case, your German 'real' opening quotes „ are on Opt ⌥ Shift ⇧ w Closing quotes ” on Opt ⌥ Shift ⇧ [
