Glue for hostile environment?

I have a customer who is willing to be a guinea pig for a roasted poplar backpacking instrument. They plan to use it for the Pacific Crest Trail where I figure moisture/heat stability/resistance would be a big plus. On the PCT some rainy days are a given as are some 110 F days, although not both at the same time. I see the roasted poplar as kind of a poor mans carbon fiber and think it might just be ideal for this application.

This instrument raises the issue of glue choices for a potentially wet location. Being on the trail for weeks or months, I am concerned about glue that might not tolerate being wet and/or hot.

Roasted poplar is a little hard to glue since water doesn't penetrate it well. In quick tests I have had some success with Titebond 2 using extended clamp times and also with hide glue. I am told that epoxy also works well with this material. Thin CA didn't work at all in my test, but gorilla glue did. Gorilla glue is way to messy IMO for gluing on sound boards or backs.

So I am thinking hide glue or epoxy, but have not completely ruled out thick CA or Titebond 2.

I like the reversibility of hide glue, but wonder how well it will hold up on the trail. Thoughts on that?

I normally avoid epoxy for musical instruments, but for a trail instrument made of roasted poplar think it might be just the ticket. It wouldn't be reversible, but it would be impervious to the potentially wet and/or hot conditions likely to be experienced.

Any thoughts on any of those glue options for this specific application? Other suggestions?