Hi Ken,
For restoring the data to any Test/Dev environments, you will first need to restore it on any Tier2+ environment.
Once you do this, you can take the JIT access of this Tier2+ environment and run SQL queries to delete old data from transaction tables.
You can decide whether you want to delete 1 year old data or 2 based on the volume of the data.
Tables which come to my mind right now are the GL tables (GeneralJournalAccountEntry and GeneralJournalEntry), Inventory tables (InventSum, WHSInventReserve, InventTrans), Sales and Purchase tables (SalesTable, SalesLine, PurchTable, PurchLine) and Invoice tables (CustInvoiceJour, CustInvoiceTrans, SalesInvoiceTemp, SalesInvoiceHeaderTmp, VendInvoiceJour, VendInvoiceTrans, VendInvoiceInfoTable, VendInvoiceInfoLine) and Parm tables (SalesParmTable, SalesParmLine) etc.
You can decide on the tables based on the report Company accounts data which you can run from the URL by appending mi=output:SysCompanySize.
Once the data is cleaned up in this Tier2+ environment, you can back it up in the Asset library (bacpac) to restore it further on Tier1 environments or directly restore it on any other Tier2+ environment.