@JasonMcD - is right if you don’t work some magic around customers and suppliers.
I have setup another company where they didn’t want to share suppliers or customers across sites, but they didn’t want to do multi-company.
Using Predictive search and a UD field, I made it easy for them to find Suppliers and Customers related to the logged in site. We also setup a BPM to prevent using a supplier/customer in the wrong site.
For GL - if you assign a GL control to the supplier - you can map a different AP or AR account to track the balance. The Aging report then can be run using the GL Controls to help you manage the receivables and payables by site.
When product is received to a Site (or Warehouse) - you can flex the Division or Department segment for splitting out your stock status to match you inventory account balance.