Probably better just to proscribe the banks. The job of the banks is to lend capital to firms and households for the capital development of the economy. So you

Probably better just to proscribe the banks. The job of the banks is to lend capital to firms and households for the capital development of the economy. So you just make any loan or activity outside that remit unenforceable for regulated banks. Banking should be boring, particularly if there is an expectation the taxpayer is on the hook in extremis.