G'day William.

I've just double checked one of the Black Wolf McKinley 65L Rucksacks on the shop floor and the label on it suggested that the Black Wolf 3L Bladder would be the best fit. 

Update 25/6/19 - Just a heads up, the Blackwolf 3L bladder will be a little long to fit in the hydration pocket on the McKinley 65L. So if you're wanting to carry a 3L bladder it will just need to sit in the back or top of the pack.

G'day Kate,

I've just had a look at one of our Black Wolf McKinley 65L Rucksacks from the shop floor. The zip on the bag is waterproof, it comes with a rain cover that can be folded away. I would suggest that the bag itself has some very mild waterproofing characteristics but I certainly wouldn't be submerging it at all. As for whether or not it'll be tough enough for an 800km walk. I would suggest that it definitely would be, providing you take good care of it. Just be careful not to dump it down at the end of a long day's hike or drag it along the ground etc. 

G'day Naomi, 

Yes, the McKinley does have a chest strap.