Yep, there is no doubt that flying the inboard wingtip is the simplest most intuitive way to steer the rudder while inverted. While inverted the rudder stick moves the same way as the inboard tip. At first I just imagined my thumb was actually in contact with the wingtip and I just pushed it back and forth to make the plane go where I wanted. I actually use my foamy to demonstrate this to people. Just flip it over upside down in your right hand, put your left thumb on the inboard wingtip and push it through the yaw axis with your thumb... Its one of the few things you can actually demonstrate on the ground. Now that my brain has caught on there is no thought at all I just do it.

The only time I use a different technique is when I am flying a vertical line with the belly facing me. Then I do the same thing but I just use the rudder stick to push the tail where I want it to go. I do this when hovering belly facing me as well.