All I will add is that I can appreciate your fear of these blind spark plugs.
I have never owned a car where you can't even SEE the spark plug.
I never changed mine out of fear of never getting the spark plug back in.
Just take it slow and treat it like any bolt
Never force it, and there should be little resistance.
Some ambiguous debate on ideal spark plug tool is in here
#6 Spark Plug. Then This Happened