This may be a little late to respond, but here you go…
Unless the camper has a compromised immune system and is asymptomatic, the CDC doesn’t recommend testing during the 90 days after the original diagnosis. I understand that camp admission rules are different, though, and the camper may test positive on PCR. The good news is that the CDC recognizes that viral shedding can still occur up to 12 weeks afterwards but doesn’t consider it contagious to others. Most of their data is in adults, but they’re saying to use the same rules with children for now.
Based on this, I’d say the camper should be allowed in camp, regardless of the test results, since they are within the 90 days of the initial infection and otherwise recovered.
Here are two references from the CDC:
The easier-to-read overview: https://www.cdc.gov/coronavirus/2019-ncov/if-you-are-sick/end-home-isolation.html
The longer, detailed info: https://www.cdc.gov/coronavirus/2019-ncov/hcp/duration-isolation.html