My Starlink Mini is in the wing so I'm not a great comparison.
That said, I think I'd be suspicious of the USB adapter too. I've had a few really noisy ones.
To that end the Starlink runs well as long as I can get close'ish to 12 volts onto my Amazon special 14ga plug (
https://a.co/d/3Vaa9YG). I ran 12ga wire from the CB to the wing which was likely overkill but it does the job even with the engine off from my EarthX batteries. If you have non-USB power readily available in the back it may be the cheap and good solution.
Running when the engine is on, anything fatter and/or shorter than the standard Starlink cable should work without a step up converter based on this sample size of one.
Derek