How about you just shoot whichever class you want to and not worry about the stakes. I've shot in two outdoor 3D's so far....and both times I've shot with guys shooting longer stakes than me. It's not an issue. Not one bit. I'll say it one more time and then I really don't care, anymore.
Shoot what you want to.
A guy I shot with today said everyone shoots the same stakes at Sage Creek. He shoots open classWITH a hunting rig.