I do not one stick, but I've read a bunch about it and watched many of the videos and it appears to me that the limiting factor is basically how far you can reach your stick while dangling from your tether.
If you have long arms or a long torso you may be able to use a 3 step aider. If you have T-rex arms or a shorter torso that some, you may be wasting that bottom step on a 3 step aider.
I thought about one sticking so I tested the water without paying the entry fee.
Install one of your sticks at a height you are comfortable with, from your top step set up your tether and dangle to the side as if you were one stick climbing. Instead of reaching down to grab your original stick to move it up the tree, reach behind you and grab a second stick you have hanging from your harness or saddle and attach it to the tree as if it were your original stick. Determine how high you placed that second stick and how long of an aider you'd require to climb it - that will determine the length of aider you'd need. You probably don't need to attach it to the tree with a cam cleat or daisy chain or rope mod as if to climb the second stick, it is simply there for you to gauge aider length.
I learned that it is not my preferred climbing method but plenty love it. I try new methods every year but keep defaulting to the safest and fastest method I can employ; Wild Edge steps with a 3 step DIY aider.
(Next year I intend to give 2TC a go...) Hahaha