I agree with your statements that it is impossible to avoid a sonic boom, but it sure can be minimized. Some time ago I read something about planes and the wall of sound. If a plane lags barely below the speed of sound for too long, it causes the plane to vibrate and, if nothing is done to prevent it, it will be shattered. If it accelerates too slowly, the sonic boom will be very loud indeed.

So, if you accellerate extremely quickly while reaching Mach 1, the sonic boom should be minimized.

The only known quantity that moves faster than
light is the office grapevine. (from Nan's fabulous Home series)