One of the main reasons I have already rooted my device (although the bootloader had to be unlocked).
So I can use "Expanded Desktop" from Xposed module "Gravity Box" (no navigation bar anymore, which additionally means more screen estate) and GMD Gesture control instead.
For instance, for "Back" I have set 2 gestures: Either diagonally (!) to the right and down with 3 fingers, or the same to the left and down.
Since "Back" is a very frequent command, this is the most comfortable direction for a swipe because the arm which is holding the tablet is anyway in that direction. I just have to pull the arm "back" instead of bringing it into a certain position first. And the two gestures ensure that I can make the Back gesture with either hand equally comfortably.
I had the device unrooted for two weeks, and it felt simply awkward to be forced again to hit little spots on the screen for basic commands. (My other devices are always also rooted.)