Dear Le Thi Cam Tu,
Thanks for contacting Top China Travel!
You are right, there are 2 ways to go when you are visit Shuzheng Valley: the outside road (road near bus route) and the inside plank wooden trail. It is suggested to visit by the outside road (road near bus route). Firstly, the bus stops are sited by the outside road, if you feel tired and do not want to walk any more, you can easily get to a bus stop to catch a bus; secondly, the sunlights play from the the the outside road side to the inside plank wooden trail side if you are visiting in the afternoon. If you visit by the inside plank wooden trail, it is hard to take good pictures.
Both are fine to visit Rhino Lake, Tiger lake, Crouching Dragon. But the outside road is better to see Reed Lakes.
At noon or in the afternoon of a day provides better view of those places that you mentioned.
Any further request or question, please feel free to contact with us.