Query security solution request: Row level (BU) and Chartfield security

UNC is in the discovery process to determine a solution to create PS Query security (actually all reporting) that integrates both Row level (BU) and Chartfield security. Since they will both be active online, we need a solution to match for reporting purposes. We are on v9.1, tools 8.53 (I understand this functionality exists in 9.2). Row level is easy since BU is a key on all the transaction tables, but since Dept (basis for our CF security) is not a key – there is no elegant solution that I am aware of.