I believe I've got all my client state units setup. Here's what I decided on.

1. Ethiopian Client Prince : Basically, a very slightly beefed up unit of Ethiopian Swordsmen. Only recruitable in 3 - 4 territories in the southeast.

2. Arab Chieftain : Recruitable throughout the Penninsula, Sinai, and Nabataea.

3. Indian Hyparkhos (Vice Regent) : Indian Elephant General recruitable in the Indian territories.

4. Judean Client King : Western Mercenaries makign up the Judean Royal Guard. Only recruitable in Judea.

5. Dosidataskeli : Unit previously taken out of the game. Will the the default cleint kings in 3 territories in Northern Iberia, and recruitable general's bodyguards in another 2.

6. Iberian Tribal Chief : Iberian Medium Cavalry, recruitable in Southern and Eastern Iberia.

NOTE : Incidentally, the Uachtarach DuboGaiscaocha have become a merc unit; and one which only spawns very infrequently in my mod.
Any other suggestions? I need some room for more units, but if anyone has any terrific and smewhat historically accurate ideas, I'm open.