The manufacturer has been able to make medium support hosiery for tall people. It is designed for men in general, but should accommodate women too. It will be 4′; long from the toe to the gusset. This should be long enough for most tall people, without stretching. Taller people can wear it, with stretching.
Your foot is probably over a foot long, if you are a tall person. That takes up 12″, which leaves 36″ of material. That means you would have an inseam of 36″ or more. I am 5′6″ tall, and I have a 30″ inseam. My size 6.5 feet are about 12″ long, so 6′ tall people should fit in this just fine.
I would like to get a feel for how many of you are interested in this kind of thing. It could cost around $20/pair, because of how difficult it is to make, and sell. It actually requires more manual labour than normal short hosiery.
Thank you for reading!