More zipline questions

[am2]

Looking to take an Alaskan cruise in 2012 with my DH, DS10, and DD8 (at the time), plus my parents. DH, kids, and my dad want to zipline. Looks like Adventure Park Ziplines in Skagway will take kids as young as 8yo with no weight minimum. But I only see them on the Celebrity excursions and we're leaning towards Holland America. There's no contact info, it just says book through your cruise line. I assume such things are not negotiable, like I couldn't call HAL and say, could you book us an excursion through Adventure Park even though it's not listed on your excursions? Dumb question probably!

 

Found a couple in Ketchikan (Bear Creek Zipline) and Juneau (Alaska Zipline Adventures) but they both have 70lb minimums and my DS might make that but no way DD will. She's going to be soooo mad! She's the family daredevil. Might have to come up with something for the girls to do- spa day on the ship maybe.

 

Has anyone done any of the above mentioned ziplines? Anyone done them with kids? I'd love to hear any feedback on them.