How are you going to attach them to your stringers?

You could run the duct thru the garage to exterior wall and terminate it there.

I rented a house in New York on a lake during Christmas of 2021. The house set well below the road, with lots of steps. They had a pulley system with a small crate attached that went to the house. A pulley at the house and a pulley at the parking area, with a second rope on the crate. You would load the crate and gravity would let it travel to the porch. We had to kind of hold the rope to keep it slow. Someone would empty, then pull it back up, and load again. After the first load, we just decided to carry our stuff down. It was pretty worn and not all that smooth. We didn’t want to chance having our stuff fall into the shrubs and rocks with lots of snow. It was mounted to a 3” steel post at the top, and bolted to the house wall at the bottom. It must have been a pain in the ass to install and tension everything.

Double headers and metal hangers. Support the cut joist while you are doing it. It’s a pretty basic framing job.

Gorilla tape.