ROWID in Customers is not automatic related to ROWID in Invoices.
As you wrote, ROWID is ever present (with AutoIncrement or not).
I think that the best way is (classic):
Table Customers:
ID (it replaces CustomerAccount) as Primary key (PK)
Name
...
Table Invoices:
ID (PK)
CustomerID as Foreign Key (FK) related to Customers.ID
Date
...
Table InvDetails:
ID (PK)
InvoiceID (FK to Invoices.ID)
...
I mean, I do not hold account of the ROWID, even though, unfortunately, SQLite instead uses and indexes it