In my home I have an open stairwell to an upstairs area, that bring light etc down to a small bedroom.
In winter it gets very cold and I am loon
king for ideas to improve things.
Invasive plants are Earth's way of insisting we notice her medicines. Stephen Herrod Buhner
Everyone learns what works by learning what doesn't work. Stephen Herrod Buhner
I met a couple who no longer needed frequent access to the second story of their house. They had built a wooden horizontal hinged platform to seal the area above the stairs to reduce heating costs.
If you need light through it, you could build it so that some areas had plastic to let light through?
So much depends on exactly what your situation looks like. A diagram and photos would be a big help.
It sounds like you could make a hatch cover that you could open when you want to use it, with something like plexiglass in it to let light through. That could also make it lighter for ease of use.