We have had big hands lift the barrier ropes and push the units with the little hands under so they have better access. "How can they truly appreciate the experience without tactile sensory input?"
For me that would be 8 fingures. I lost most use of my trigger finger and the next to it back when I was 12 and on the farm.
On the layout itself, I will use the 0-5-0. Especially given most of my Tortoise machines, although wired and all installed, don't have motor power yet. Only about 10%. This is my 3rd edition of the Albemarle Division and I found the more I got done wiring the layout, the less I used the 0-5-0. NOW. My current staging yard is a playground to wallow in the hand action. I built it for staging and even spaced the track centers out to get fingers in-between. Also wasn't bashful about putting the Tortoise machines on top of the layout because it is not a modeled yard in the pure sense of the word. Here's a shot my "hand friendly" staging yard several years ago when it was under construction.
" even spaced the track centers out to get fingers in-between." Great! Idea! I think I'll be applying that was well.
Since my entire system is still under development, I use my fingers most of the time. Sometimes I use a small screwdriver as "push pole" too.