How about using something natural that will last longer than oak? In the midwest there is a tree called the osage orange ( commonly called - hedge). When fresh cut it will mill as easily as oak, it has a pleasing pattern as oak, it is stronger than oak and will not rot ( in your lifetime).
Fence posts made of this material have been in existence over 100 years in this area. Old hedge rows produce quality saw logs that yield 8 ft or longer logs with boards up to 12 inches wide.
