Given equality of arms, it only takes a 10:1 advantage in numbers to defeat any static defense. This has been proven time after time all throughout history. If you think you can remain hidden, well, guess again.
the trick will be to survive, hidden, for about 6 months (and thru a winter).
that would kill off most of the population via starvation and various ‘struggles’
being remote would help but you also have to be ruthless... as the ones you’ll meet after that will be the toughest survivors