@LlamaMountainStudioArts
6 1/2 winter hours?
Oh hey, I have that exact Renogy kit.

The problem can be reduced to:
Winter solar gain is meh.
Batteries hate cold.
Panels are relatively cheap.

So my .02 is Buy panels until they can keep the batteries charged in December.

For actually calculation, it's not rocket surgery, just a bit of multiplication. I think you _need_ 3 panels and want 4 or 5.
See:
https://dotwatts.com/solar-panel-size-calculator/