If they are being hand delivered, I also chuckle at the special shipping requirements. If I were the customer, I would rather not see them bagged at all, but rather placed in a cooler with air and heat. This way, water changes can be performed if needed and a close eye can be kept on them. BUT... if you are an experienced shipper, I would prepare them as if you were shipping them. 20 hours is fine, especially since you know what you are doing...