Using a shad saver or non iodized salt will help harden the scales but that's good to know as well!!

You can make a smaller, portable shad keeper pretty easily and cheap. But no matter what you use, plan on 2 alewives/threadfins per gallon or one gizzard per gallon. There is no getting around that no matter how good the tank is.. Any more and they won't be worth putting on a hook unless you are doing well with cut bait.