You need a permit and a guide as it is a National Park. Some mountains like Chilai Shan, HohouanShan don’t really have anyone checking, but the route from Yuli has a checkpoint just after the last aboriginal village. Mucha Man, you might be more up to date on the permit system than I am. I’m not sure what the criteria is for being a guide, but I’ve heard it is being able to prove you’ve climbed 30 or more peaks over 3,000 meters. There are six huts from Yuli to Patungkuan meadow, but a tent is still essential as there are long stretches between some of them. The park on the Hualien side goes down low enough in altitude to include the habitat favored by monkey, barking deer,wild pig and bear.
About me, I’m a new poster on this message board, but I’ve been hiking pretty regularly (60 to 90 days per year) for the last 11 years.