Fixed Fee Payment Under 52.216-8 – Lump Sum Option at end of PoP?

Long-time lurker, first-time poster. I am administering a CPFF contract with 52.216-8 Fixed Fee included. The KO did not provide a Schedule for fixed fee payments as referenced in the clause.

Through a quirk of our accounting system (and strong cash flow position), it would actually be beneficial to us from a financial management standpoint to bill for all of the fixed fee at the end of the PoP instead of incrementally billing throughout the contract based on percentage of work completed or cost incurred. 

Before we speak with the KO, are there any limitations on proposing this billing plan? I did not see anything in the FAR preventing it, though not sure if DCMA or DCAA has any internal guidance against this methodology. 

Thanks!