Well, from what I've heard, Tenchi marries all of the girls.

BUT...
1. Ryoko
2. Sasami/Tsunami
3. Ayeka
4. Washu
5. Mihoshi
6. Kiyone
7. Ryo-Oki

And since Sasami is over 700 years old, she would be able to marry him at her current physical age.
I hated Sakuya because she broke up the family, however unintentional it was, and she died already, so she doesn't count in my book.

Back on topic, minimum should be none, and there should be no maximum.

Tenchi is likey seventeen in Tenchi Muyo Ryo-Ohki OVA 3. He does notice that Ryoko,Mihoshi, and Ayeka have strong feelings for him. He is overwhelm by the affections of the three giirls. Tenchi will come to his senses.

My choice for Tenchi's first wife is Ayeka. Tenchi will likely have to confront Ayeka's father King Azusa. King Azusa will have to challenge Tenchi to see if he is worthy of Ayeka and Sasami.

My second choice will be Noike. Noike is supposely engaged to Tenchi. She has started to show feelings for Tenchi. Ryoko is my third choice. She still needs some growing up to do. My fourth choice will be Sasami. Because the Kuramitsu Family has a strong prejudices when it comes to mates, my last choice will be Mihoshi. Tenchi will have to convince Mihoshi's family of his worthiness for her. Likely Mihoshi's family will allow Tenchi to marry Mihoshi because he is second in line to the throne of Jurai.

Summary of ordrers of marriages.

1. Ayeka
2. Noike
3. Ryoko
4. Mihoshi
5. Sasami

Welcome to the board Takahata ^_^

Unusual to have a Noike fan here, but all is good.

...as a test subject she feels for him. xP