Yes, you will need to follow the approval procedures for individual deviations at DFARS 201.403. Although your proposed deviation makes the reporting requirement tighter than the 72 hours prescribed by the clause, it is in the Government's interest to minimize the administrative burden on contractors, wherever possible. You’ll notice DFARS 201.403 does not provide an exception for the tightening of requirements contained in clauses. If DFARS contemplated allowing contracting officer discretion when setting the reporting requirement, it would likely have provided a fill-in space in the clause for inserting the number of hours .