How to limit the requisition BUs when searching requisition lines?

We're a county government with a setup of one procurement BU and one requisitioning BU per department. What I'm trying to do is figure out how to implement security in such a way that the user would be able to see records on the View Requisition Lines screen for only requisitioning BUs that they have been given data access:

In order for the BU dropdowns to populate, it seems that I need to be a Procurement Agent with the View option set under Manage Requisitions. This seems to have an all-or-nothing effect, as it gives me all of the departments (requisitioning BUs) regardless of my data access or lack thereof.