I’ve outgrown the single leg squats. Now I have to get back to doing barbell squats.
I was doing single leg squats with a weighted vest on, and started holding my computer above my head for xtra resistance. 
Still, it became more about balance for everytime I added a new resistance it changed the technique of the exercise.
I’ve moved town and I’m about to buy a whole new set of weights.
The bar squats and cleans are so much better.
I think that barbell work is so much better than compromised caveman type training.