I commend you for trying the rescue route! There ARE rescues, especially breed rescues, that will take dogs that have bitten, IF they feel they can rehab them. Those dogs get fostered by people who know how to work with dogs with behavioral problems. This would not be regular rehoming and they would warn any potential future adopters of the dog's past......you wouldn't be doing something irresponsible so long as they are fully aware of the dog's past behavior.