jim wrote:

....
No matter what you choose to do, pay particular attention to
connection details because no matter how strong the members are, if
the connections fail, the fence will weaken and in time fail.

Sage advice...in arid climate (even more so than ours) following will
last a long time (TM)

Simply drill through the post and attach horizontal rails w/ carriage
bolt. Run rails, need not concern about matching ends at posts...use
either a 2x4 blocker or a flat strap at joints and bolt there. In wet
climates there's an issue of water entrapment at the joint but where
it's dry like here they lasted, as I said above, 30-40 years w/ no
attention. Grandpa/Dad set 8' post space and ran 12' to 16' rails.
Actually easier than trying to capture both ends on a single post
(although 4x4 posts are easier in that regard than the round posts
here). The rails were/are Doug fir which weathers well, albeit is now
expensive...but this was done before treated was available.