They are I beams. FIL is a machinist of 35 years. Lots of things made from leftovers from projects he was involved in over the years.
I've stacked at night when it was the only time I had. It's not so hard to do in the dark or with a little bit of moonlight. Course with all the neighbor's outside lights it's not exactly pitch black dark either.
I'm a night person, and it's not unusual for me to be out after dark running the log splitter, of course after dark isn't late this time of year. But we have some neighbors that are in bed by 8:00, so I try not to go too late.