Try this:
Find an empty lot and set up two lines of plastic cups to make a lane. Start about 8' width.
Think in your mind how when a top spins, it wants to stay up no matter where you push it. That motor spinning will have the same gyroscopic effect.
Do the trail braking and keep your revs slight higher than stalling it out so it purrs. Keeping steady pressure on the rear brake, so it drags, try creeping along your lane.
Keep your eyes up and think of the gyroscope of the motor.
Once you master going about a fast trot, try going slower.
One you master that, start narrowing the lane by half.
Air the bike out very 10 or 15 minutes to keep it from overheating.
and finally, stay calm.
I hope this helps. Eventually you will become in control enough with the bike that you can stop for a couple of seconds without needing to put your foot down.
You should record your endeavor, it could help encourage you when reviewing it and other watching. Maybe one camera with first person point of view and then a second watching where you can see the whole lane from third person POV.
If you have a bicycle, you can try it first that way to build your confidence.