No, I don't like.
You're playing SM-style games, getting carried away with the decimal places whilst your basic assumpmtions are wildly wrong.
For a self-supporting tower, aim for a height to width ratio of around 10, otherwise you have to get smart in internal bracing.
For a 50 MILE tower you need 5 MILE baseline
78 feet is as pointless as 48"
Stop finessing your cones and go get real.
