Danai Gurira (Michonne from The Walking Dead) has the kinda face that would fit well.
Hmm... Are we going for clone wars era AT or a more grown / matured look?
Chronologically she should have been about 18 by the time TCW ended, but still didn't have full-length head tails or horns. Or at least, not like Shaak Ti's. Maybe Togruta pysically mature slower than humans. Or maybe it varies from individual to individual, and some of them never develop long ones.
By the time of ANH she would be 37 - 38, and by the events of ROTJ, 41 - 42. Older than Luke, a lot younger than Vader or Obi-Wan. About contemporary with Solo.