a comma followed by a possessive apostrophe

I think this is a stylistic difference. I don't think you'd find anyone decisively saying it's grammatically correct or incorrect. The more common conundrums are with name suffixes, like PhD and Jr. "John Doe, PhD's résumé is impressive," looks quite awkward. "Jr." is even more awkward because it has a period.

The Chicago Manual of Style says "when a word ends in an apostrophe, no period or comma should intervene between the word and the apostrophe."

http://www.chicagomanualofstyle.org/qanda/data/faq/topics/Punctuation/faq0018.html

But conveniently, they don't suggest a solution...

I think that the best thing you can do it those kinds of situations is try to rephrase the sentence in order to not make it look so awkward.
Generally speaking, those examples you have look correct-ish but it's debatable.

In those kinds of awkward situations, the best thing you can do is try rephrasing what you said to make it sound less weird. Rewording it can help smooth things over.