Transition from PhD to postdoc with an intent to change field
As one of my advisors once told me,


  The best dissertation is one that is written.


Tounge-and-cheek as it may be, I would strongly advise finishing up your PhD first, especially if you can do it in three months.  If you have doubts about whether your committee will approve your work, then you should be having that conversation very frequently (at least once a week, if not more) with the committee members that you think will have an issue with the work.

If you are indeed "certain [you] want to pursue an academic career," choice (2) may be the hardest path.  I've known a number of people who were certain they wanted to move back into academia after working in industry, but they didn't publish enough once they had a full-time non-academic job, and they weren't competitive for future academic positions.

Choice (3) would be a soul-killer if I were in that position.  To see the finish line three months away and then scrap it for 2-3 more years of work?  Not for me.

Choice (4) would probably be the worst decision -- every day you stay unemployed lessens the chance someone would eventually hire you (although maybe there are a ton of post-docs in your field).  Proving that you've learned these things on your own is difficult, although you would have more time to publish (but will you have a university association still?).

Tough choices all around, but I suggest finishing up the PhD at least.