Yes. For my stacked match plans I calculate the exact percentage for the fixed match and simply amend year by year as needed.
Amending each year is just one of the many challenges/costs associated with maxing-out owners under a match arrangement. You avoid the costs of a profit sharing approach, but you certainly pay for it with complexity. Risky too. You should see what happens when the new guy down in shipping & receiving actually reads the safe harbor notice, raises his deferrals & convinces the other NHCE's in the break room to follow suit on Dec 15--That gets expensive real quick.