How to store directional light shadowmap?

Basically, I have game where you fly around in a spaceship in third person and can get out of the ship in fps mode.

When you’re in the ship, the shadow distance is set to 2800 for really large enclosed flying areas.

When you’re in fps mode, it’s set to only 500 to decrease shadow pixelation.

I need a way to store and reuse the shadows when I switch into fps mode so the huge enclosed spaces stay shaded and not magically receive light because of lack of shadow distance.