The Dutch sealed a second-round spot on Wednesday following a thrilling 3-2 win over Australia in Group B, Spain's 2-0 reverse to Chile later in the day confirming their qualification.
Van Gaal and his men conclude their group phase with a clash versus Chile on Monday, in a game that will decide who finishes top of the pool.
Jonathan de Guzman and Stefan de Vrij are one booking away from a second-round ban but Ooijer, a veteran of three finals in the past, warned against too many changes.
"Keep the spine as intact as possible; don't throw the team into confusion," he told De Telegraaf.
"If you give someone a rest and his replacement does really well, you have another decision to make.
"And that's not necessary. In preparation, everyone is fighting for the place.
"As the tournament begins, it becomes clear. Why would you open the competition (for places) in the middle of the tournament?"
