Yes you can - for reporting purposes only.
Throughout the year use the Inventory tab and Inventory - Cost account as per normal.
Modify the chart of accounts to reflect the opening - purchases - closing format by adding the the opening and closing stock account and renaming the existing Inventory - Cost account to Plus Purchases.
So you have gone from this to this using your figures:
At year end create a Journal Entry to enter the P&L adjustment for the closing stock:
And the P&L becomes:
At each subsequent year end create a Journal Entry which reflects both opening and closing stock.
So the P&L would look like this before any new year “Inventory - Cost” transactions.
No you don’t. Review the above examples.