I have a son with mild autism. He is currently attending virtual school because he was struggling in regular school, even with classroom supports. In our situation, I would be extremely apprehensive about letting him go on such a trip. Autistic kids crave routines and rules. They do best when they know what to expect. They have trouble with emotional regulation and tend to have rigid thoughts and behaviors. They are also socially awkward. All of these things combined don’t seem compatible with the trip’s open-ended agenda IMHO.
However, autism is a spectrum disorder and some autistic kids are high functioning and do quite well in a mainstream environment with neurotypical kids. My child would probably be okay for the first day, then have meltdowns for the rest of the trip. Being away from home for an extended amount of time without a chaperone equipped to handle a difficult child sounds like a disaster in the making. Perhaps you can persuade the parent of the child in question to be a chaperone on the trip?