Gosh, the school counselor should surely be more helpful than that? Teachers I can understand are trained to teach and may not understand phobias but I'd have thought a counsellor should be more sensitive. Good on your DD for trying to talk to them.
I agree with PP that she shouldn't have to confront this by herself in front of all her peers. Even if she did cope, the stress of the anticipation is probably awful for her. She should know she'll be catered to so she doesn't have to worry, and can look forward to the trip like all the other kids.
I too would go in and make myself heard, and ask for some sort of low-key workaround
