On Sunday, October 22, 2017 at 12:12:32 AM UTC-7, Andy Blackburn wrote:
On Thursday, October 19, 2017 at 2:23:34 PM UTC-7, wrote:
I have a camel back. What if I also want to have a thermos with some ice and pepsi to enjoy a sandwich? ...

Here's a picture, works great.

http://sc02.alicdn.com/kf/HTB1sgi3KF...Holder-Hat.jpg

Or go to Amazon.

https://www.amazon.com/SUCTION-HOLDE.../dp/B00A80CHMQ

I don't recommend this sort of thing. Bulky objects get in the way, jam things. Sealing the open container, stowing the cap invites distractions and complications. Best to keep things simple. It's no picnic up there.