I've been "studying" UFOs for over 50 years, though I confess my interest has waned in the last couple of decades.
The big issue for me has always been the coy aspect of UFOs. (I have similar issues with God.)
Why do we get only tantalizing glimpses repeated over such a long time period? What are we supposed to get out of these fleeting observations? If they are so advanced, either we'd never see them, or they'd be on the White House lawn!
First, while there are certainly some crazies and some hoaxers, it's pretty clear that most observers are perfectly sincere individuals reporting something they actually saw.
Second, it seems clear that a majority of those observers are seeing something explainable - atmospheric phenomena, or human airplanes or airships.
But that still leaves a core of reliable, honest witnesses reporting unexplainable things.
It is my sad opinion, shared by at least some other UFO researchers, that what they are seeing is the US military.
For decades now, there have been rumors that "they" have a device that allows them to project radar "bogies" - images that appear to be aircraft on a radar screen but aren't actually there.
In particular, I would point you to two cases of those bogies about 1 year apart, around twenty years ago, one involving the Mexican air force, and the second one involving the Iranian air force.
So what about the visual sightings?
It's my belief that this is a similar projection device that produces visual images, paid for with Our Tax Dollars At Work.
In particular, you mention the key point of the G forces. UFOs have been observed performing maneuvers that would subject them to accelerations approaching 1000gs.
You're right that no organic structure could survive this, but no technological structure could either! Think "one kilogram supports one tonne."
Or look at a car accident. Car accidents involve G-forces of around 50g. Imagine forces 20 times as great as this.
If these are just projections, this isn't a problem at all. Indeed, one of the defining characteristics of projections is that you can get apparent velocities of any magnitude you like, or change directions abruptly with no acceleration.
Thanks for an interesting article!