Just a thought.  Create two invoices.  One for the first two years and one for the second two years.  Just make sure the posting dates are the same and in the current year.

No, that's not going to be acceptable.
We're working the invoices in the background and setting the due dates after they have been created, but that is not ideal.

I agree, this doesn't even work for 3 years.  I see they haven't change anything here yet. 

If someone has a work around please advise.

Use a due Date table. Can add up to 999 MONTHS in that config. Only good for 1 due date though, not recurring

Sorry, but since due date table only allows one date, this does not work.  We must have the correct amount due on what dates for the entire 36 months.  (Like a payment plan would be laid out for say a 36 month loan).  This way also, statements can be modified to show current due and future due amounts for these invoices.  Thanks though!

Sounds like a job for an add-on module.  dingosoft  Ledger Manager might help and I'm sure I've seen others in my travels.  Try the market place?