I'm planning to build a ~250 linear foot wood fence around the backyard of a home in Oklahoma City. My question / confusion revolves around burying the posts.

Details:

• 2 x 90 foot runs
• 1 x 50 foot run
• 2 x 10 foot run (both to connect the long sides to the side of the house, 1 with gate)

What I know:

• Oklahoma City requires a permit for building fences on residential property, looks to be $22.
• I've found the resources I'll need to have utility lines marked so I can avoid those (free!).
• How to determine where to bury posts.
• Basics of assembling and mounting fence panels.
• Oklahoma City's frost line depth.

Where the confusion is: On DIY / How To videos, everyone always installs post like one of these options:

1) Dig hole that's slightly rounder than post, drop in post, pour concrete around it.

or

2) Dig hole that's slightly rounder than post, pour a few inches of gravel at the bottom, drop in post, pour gravel around it, build up small mound of gravel / dirt slightly above ground level.

The first option sounds terrible because concrete / quikrete is porous and will likely just lock in moisture like having a sponge around the fence post and it'll likely rot pretty bad in 2-3 years time. It'll also be a pain to replace the posts since I'll have to pull up the concrete with the post.

The second option sounds terrible because even with gravel, there will still be a lot of water near the post, and it'll especially pool during heavy rains since the layers of clay in Oklahoma are slow to soak up water. I give this 4-5 years before the fence posts have rotted pretty badly.

Now, the above suggestions were all made on Lowe's / Home Depot / other DIY blogs (I even saw a wood fence on /r/DIY that looks like the posts were just buried in dirt) -- however, they all suggest the following for the posts of a wood deck:

3) Dig 6 inches below the frost line. Place a few inches of gravel, pour in concrete / quickrete with an embedded anchor bolt exposing ~1 inch of threading. Attach a post bracket to the anchor bolt, then put your post in the bracket.

Option 3 seems to be practically the same amount of work as options 1 and 2, uses a bit more concrete, an anchor bolt, and a bracket -- but that supply price difference seems pretty small - and since I'm not burying any of the post, each post can be ~2 feet shorter than options 1 or 2. The difficulty seems about the same, yet the ability to easily repair / replace posts later is much better.

So my question is basically:

Option 1, 2, 3, or some other alternative for burying the posts.

Bonus question:

I know I need to dig past the frost line, but how far past the frost line?