Comment by ToValueFunfetti

It depends on how you define the bounds of the Solar System, but eg. a flight from Pluto at its most distant to the same distance on the opposite side of the sun that hits .1C at peak needs ~5G for the entire duration. And it seems quite wasteful to bother getting up to speed before immediately reversing the acceleration.

If you're travelling between points in the Oort Cloud, 1G should be more than sufficient to hit .1c on the trip.