Generally, if you contact the camp hosts that you are leaving early (by check-out time the day before), they will issue a refund. If you paid by credit or debit card, you will see a credit to your account fairly quickly. Cash refunds take longer. The key is to notify the camp hosts as quickly as possible, so they can post the site as available.
Contact recreation.com where you made reservations but most likely you won't get refund but doesn't hurt to try. Good luck
Thanks! Your answer is awaiting moderation.