Hi Dan,
The QBO Location field is actually located on the individual transaction tables, not on the Customer table. It’s a stand-alone field that is set individually on each transaction independent of the customer record. As such, you’re going to have difficulty using this field for the workflow you described.
If you’re going to be managing this exclusively in Method, you may want to consider adding a Method custom field to the Customer table for this instead. A dropdown field containing a choice for each of your territories should suffice. Just keep in mind that this field will not sync with QBO.
I hope this helps.
Audisho