Just experienced our first Non-refundable campground

If the campground is open and usable you may as well go that far and enjoy the stay. Maybe it is nice and stay a few extra days and make it your destination.

Works the same for your non-refundable flight to the non-refundable hotel to utilize the non-refundable excursions.

If you want the option of a refund, that should have been part of the original booking and very often comes at a higher price.

Otherwise look into some travel insurance to cover these costs.