Green’s Dictionary of Slang

(US) a minimum security prison.

1984		Arizona Republican (Phoenix, AZ) 31 July B1/5: Home away from home; health resort; summer camp — A minimum security prison [...] where prisoners have more freedom.
2008		Simon & Mills ‘React Quotes’ Wire ser. 5 ep. 5 [TV script] You go away for a year or so to some minimum-security summer camp.