Probably the most recognizable source of supplemental oxygen for those of us who need it are our friends the green-topped sliver tanks. As you know, they come in a bunch of different sizes, each with its own capacity and uses.
How do you transport your bottle? Do you use the big E bottle with its cart? Would it be easier for you to use a smaller bottle with a shoulder carrier? How about a slightly larger one or two smaller ones with a backpack? The smaller bottles are certainly easier to store, carry, and replace.
When I was on supplemental oxygen, I personally liked to carry one of the medium-sized ones or a couple of the small ones in a backpack. It left my arms free, it was easy to put on and take off, and if I didn't need it, I could store the cannula inside of the pack. Maybe somebody would think that I was actually capable of hiking!
When I went on O2 full time, I made it a habit to carry two tanks of the same size in a backpack. I would take off on a full tank and walk, secure in the knowledge that, if I emptied it, I had enough oxygen on board to make it back home.
We do what we have to do to keep our oxygen saturation at safe levels. Not to do so is simply self-destructive!