Not sure what the issue is? Aside from having really good water, commercial bubbler, keeping bait in a big bucket is not easy beyond 3-4 days.
I know a few guys who catch smelt and keep them all winter. They actually are outside the 10 day rule as the have the endorsement on there license
to catch, transport an use smelt from approved waters on other approved waters. For example you can catch smelt from Seymour, Willy, Joes, Peacham
get the baitfish endorsement on your fishing license and use those smelt on other lakes within East or West region were the smelt were caught.