To me the solution is not necessarily advocating for yourself, but having a system in place that is more flexible. It is not hard to imagine that not everyone in the class will be able to do the ropes course; therefore set up an alternative or just schedule something that is accessible in the first place. It is not hard to imagine that not all your students might not be citizens... so build this into your assignment.

HS Guidance counselors, in my experience, are totally inept, though.