Huel on the go

What is your solution for preparing multiple huel meals when you don't have access to a sink/kitchen? I usually put one meal in my blender bottle and I keep a large water bottle with me. I have containers for storing extra powder but once I've used the blender bottle for the first meal it seems like it wouldn't be safe to continue using the bottle without cleaning it. I was thinking I could buy a few 500ml plastic bottles and fill them with premixed huel + water and keep them in a cold lunchbox. Any other ideas?