WK95 :
What exactly does Windows not like about booting from an external drive?
As you mentioned, it requires workarounds.
And you're trying to push the data through the USB port, which introduces its own slowness.
The only need to run it from an external is to move this back and forth to new hardware. Which then introduces licensing and activation issues between the multiple systems.
Can it be done? Yeah, if you want to go through that much work.
May I ask why the desire for an external drive vs an internal one?