If I'm having my dream cupholder on my dream bag, I want it on the shorter side so it doesn't make the bag wider when turned sideways, and I want it to pivot so the coffee stays upright and doesn't spill when I tilt the bag onto 2 wheels. I don't know if it's possible to design that strong enough not to breaks and slim enough not to make the bag interior smaller, but that's what I'd like.
Thanks swag, this might be seem hard to achieve for now, but we will give it a try. If it is done properly, it's a better solution for now.