I used Wild Edge Stepps this past year. I bought 8 and used 3 for the platform. I regularly got 18-22ft with using a whoopie sling aider. Check out WE website (
https://www.wildedgeinc.com/store/p32/steppladder_aider.html#/) when you buy your steps, they sell the aider I am talking about. I have rope on hand and made my own. It works great.
I basically made the loop as large as I could, stepped in, then lifted my foot and tightened the loop to force me to take the largest step I possibly could. I can get 3-5 ft (depending on how many layers of clothing) between steps. 6 steps gets 18ft, one on each side of the top step for the platform. Sometimes, if I needed the extra height, I would only use 2 steps for the platform.
For a single step aider the whoopie sling is my preference.