Everytime I've visited there has been no issue getting one of the soaking tub rooms
You don't have to. But it's first come first serve if you don't set up a time
Typically you do not need to reserve a bath in advance. They are rented by the hour. If the camp sights are full it wouldn't hurt to reserve one in advance.
If it's a busy weekend it's good to do that. Otherwise they are generally available.
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