I'm not sure exactly how I came across this thread, but if the OP is still lurking around, despite asking for something roughly unattainable, I think I have this one figured out:
Don't taper the pole. The goal here is to match the strength of the section to the stress applied, and keep the center of gravity as low as possible. You can do that by tapering it, like the big boys do, but not cheaply, as is obvious to everyone here.
So instead, work on tapering the thickness. If the pole was 70mm the whole way up, but the wall reduced from 3mm at the base to 1mm or whatever at the tip, you end up in the same position. Better, actually, as the bending strength of a big thin hoop is better than a small fat hoop.
So chemically mill it. Stand the pole up on end, put a rubber stopper with a small hole in the middle on the base. Run some tubing from that hole to a catch drum.
Mix up some pretty dilute muriatic acid and fill the tube up from the top. It'll slowly drain out the hole at the bottom. So the top will be in contact with the acid for maybe ten seconds, and the bottom for maybe two minutes, or whatever. Everywhere in between will be a smooth transition from one time to the other (assuming you can pour fairly fast)
You'd want to size it so you etch off a couple or ten thousandths per fill, and just keep collecting and pouring the acid (you'd have to make up for what's consumed) until the top side is as thin as you want.
You'd probably want to do the process development on smaller test poles to be cheaper, but this will 100% work, is reasonably safe and is very garage friendly. All you'd really need is a tall ladder, or a roof, or a pit.
Sorry for the thread necro