Isn’t there a FAA rule about HAM tower height? Seems to me that would indicate your airspace height.
No, tower height does not indicate airspace ownership.
The height regulation is particularly important near an airport. Other than that, it is an issue of at what height you must install a beacon on top.
Where I live I can put up whatever I want. At some point it would require a beacon on top. I have no intention of having a tower of such a height.
I’m not afraid of towers, spent a couple of weekends working on one that was really tall. I did not get higher than 1350 feet on it but it was somewhat taller.