I think there's a difference between "I really don't like" and "I don't really like". The former is putting the emphasis on "don't like", increasing the degree. The latter is reducing the emphasis of "don't like". Sometimes used when you want to be polite.
I don't know enough to help you with that. Hopefully someone more experienced in the language will stop by. But just wondering though, if you wanted to say you really don't like hiking, wouldn't you say 我真不喜欢爬山 ?
This sentence does not express a strong opinion in English, and I get the impression that it does in Chinese. "I really do not like hiking" would be a stronger expression of dislike for an English speaker.