So, basically you would be a vilain then?
Fusion, we are currently 100 years away from “true” fusion power. Notably, capturing the gamma potential is far beyond our means. In the sun the gamma release bounces around for approximately ONE MILLION YEARS, ricocheting through a wall of gas 50,000 Earth thick before emerging as the soft glow of sunlight we see. Notably, at the very core that plasmoidal gas is 13 x the density of lead, moving towards the density of water before it reaches the surface.
And then there is the acceleration of counterweights towards the speed of light. Acceleration of 1kg to 99% of the speed of light gives us 7kg of relativistic mass. So careful pulse width modulated acceleration of counterweights of a fraction of the base “craft” mass would make the craft fall up! You would need to manipulate intensive electromagnetic fields to do this safely.
Well, the user guide for the physics of the universe might be powerful and speculative, it still doesn't allow wrong physics anyway.
Your relativistic counterweight doesn't work. Relativistic mass increase is internal to the system. Conservation of momentum doesn't care how fast your counterweights spin. You still need to eject mass.
You have unlimited range with that open question, I'm sure you can find correct amazing physics to suggest :)
Lorentz field displacement is another example.
You merely need an extraordinary amount of potential, hence the true fusion and optimal gamma collection!