Change it so that it is closer to basketball, where the ball is not OOB until it or player touching it is OOB.
This far simpler and less open to interpretation/error.
In the photos above OOB is called on Robbie Gray as he has possession of the ball and is over the boundary, even if the ball isn’t. And possibly the most famous of all... Wayne Harmes is not OOB as he has not been grounded OOB and neither has the ball.
For OOB on the full if a player can launch from inside the line and touch the ball before he hits the ground and the ball hits the ground then it’s a boundary throw-in. Likewise if he launches inside, marks the ball and lands outside the boundary.