Good post drewbocop.
You're right, one of the worst things about having a kratom habit are the "logistical" aspects. But I've noticed that if I act completely natural, as if it was the most normal thing in the world, then most people don't think much about it (many don't even seem to pay attention).
I always try to prepare my daily dose beforehand though, I mix it with water and carry it in a random bottle, right now I'm using an Arizona blueberry white tea bottle but I change it often (mostly because it's bad to reuse plastic bottles). I'll use anything as long as it's opaque or has stickers that prevent you from seeing the liquid inside, this isn't mandatory but it adds an extra layer or discretion that can prove to be beneficial (for example if you're in your workplace). A stainless steel thermos might be the best alternative but I don't currently own one.
Once in a blue moon someone will ask me about my drink. I'll give different answers depending on the person, but here are a few ones I've used in the past: Matcha, a natural product, a natural product that's supposed to be good for you, chlorophyll, yerba mate, a green smoothie, I don't even know what's in it but x person told me it helps aid digestion, a disgusting green slurry, etc...
Long-term relationships are built on trust though, so in that case honesty would likely be the best approach. That being said, one doesn't always have to be 110% honest, there are many ways to tell the truth.