Arbuckle Wilderness was great years ago when our kids were young. Now waiting for an opportunity to take the grandkids there, so our information is a bit outdated. Yes, there are mountains, by Oklahoma standards. The Arbuckles aren't very high above sea level, but they are rugged and great scenery.
Don't miss Turner Falls, if just to look at the waterfall. If it's warm weather there's a great swimmin' hole at the foot of the falls.
Don't know about camping at Arbuckle Wilderness, but there are campsites at Turner Falls. Both have good websites, but I don't know the URL.