Just because you will be in a crowd of 85 doesn't mean you'll get COVID.
If you do more than 10 days before your cruise, by CDC guidelines you are OK to go on the cruise as normal. 5 days to isolate, 5 days afterward to wear a mask, after that you are normal again.
You should test negative two days before your cruise with a rapid antigen test, and if you do then I wouldn't fool with the document of recovery. Just show the negative test and enjoy.