Finishing PhD and didn't secure a postdoc position: how to proceed? Disclaimer: My PhD supervisor, while not a bad person, is a bad mentor and has given me bad advice in the past. So discussing this with him isn't really productive. I have talked to other people in real life about this, and the opinion of this community would also be welcome.

I'm set to finish my PhD in theoretical physics in September 2020. I applied to several postdocs, got three interviews, and in one I was rated among the top choices but, in the end, I didn't secure any position.

I don't know how similar this is to the fields, but for context I'll explain how postdoc appointments work in (edit: high energy) theoretical physics. In my field, postdoc applications run in cycles. The majority have roughly the same application periods and deadlines (around November), most offers are made at the same time (early January following year) and they all start roughly at the same time (September). There's the occasional outlier, but that's the basic pattern. This means that it's more or less hopeless that I can continue looking for a position, ask professors, etc, for September 2020. If I wanted to stay in academia, I would need to look for a postdoc in the next cycle, starting September 2021.

I am unsure how realistic it is for me to try again or if I should simply throw the towel and quit academia.


First, there's the issue of staying one year academically idle (obviously not professionally idle, that would be insane). I could work on leftover projects from my PhD on my free time, but between finishing my PhD in September 2020 and the deadline for the next cycle on November 2020, that leaves very little time to do so. 
Second, how do I even explain the gap in my cover letter? If I flat out say I failed the previous application cycle, it's a guaranteed trip to the garbage can. Some people have recommended me just lying in vague terms, like I didn't pursue a postdoc immediately after completing my PhD due to "health concerns that have since been resolved". I'm unsure if this is a good idea...


If anyone has any other advice regarding my situation besides these two concerns I've raised, that would be welcome too. Basically, I would like to stay in academia as a first preference, but I have no desire to bang my head against the wall against something that, at this point, might be very close to impossible. I don't have any preference for country to work in, so feel free to give country-specific advice.
One option possibly available to you are academic jobs that are more teaching-oriented.  While (in the US and Canada) hiring for permanent teaching-oriented jobs is mostly over at this point, there is still hiring going on for temporary positions, both full-time and part-time, both at four-year universities and community colleges.

Such a position maintains an academic affiliation.  Not being a physicist, I do not know how taking such a job would be perceived if you apply for research-oriented jobs in the future.  I expect these positions (especially full-time ones) would be viewed positively in applications for permanent, teaching-oriented jobs.