What is the ruling on a man approaching and touching a woman over her clothes to the extent necessary to help her set up equipment for riding a zipline, when there is no female assistant available?

It is not permissible for a man to touch a non-mahram woman without necessity, even if there is a barrier. Play and amusement do not constitute a necessity that permits this. Therefore, one must repent from this act by regretting it, ceasing it, and resolving not to return to it.