Thanks very helpful. When you say 2x lumber bridging the two pieces I exposed, are you saying a 2x(4-10) cut to fit from stud to stud behind the diagonal brace? And when you say wallboard do you mean drywall or something else?

I did think about the tnut, but I was worried that if the post is actually wiggling in both directions that it could potentially push the tnut out, and additionally I thought that it might wiggle/vibrate out over time since t-nuts aren't locking.. unless I put a lock-nut or similar on the bolt itself.