None of the above fits what I'd do.
A-Jax is the starter for me. I'm shocked that people are questioning it; unless Alt or Fashanu somehow falls to #19, I'm not interested in replacing him because he really is a solid, ascending left tackle who has improved with every game.
But I would absolutely draft a left tackle replacement in Day 2 for after next year; it would be foolish to rely on Noteboom at this point, A-Jax will be a free agent after, and since we've already sunk so much cost in the offensive line, I don't think we re-sign him.
So, basically, draft a Day 2 left tackle to learn under A-Jax and Havenstein, be the swing-tackle for this year and take over the empty left tackle spot next year.