You make a good point about the ethylene speeding things up. Do you think it would help to have a fan running at low just to keep the ethylene blowing away?
May be, but it may also dry them somewhat. I know my mother kept green tomatoes almost for three months by having them in cool room and removing all turning red from storage. The last tomatoes to ripen were also dry…
This is highly variety dependent. Most garden tomatoes can be stored between 3 and 10 days if picked just as they start to turn colors. Cooler is better up to a point. Do not store in the refrigerator and don’t store them anywhere below 45 degrees because it is very bad for flavor. A cool basement is ideal, up on a table. Don’t store them if they are damaged. A worm hole or other damage to the skin will cause it to rot as it ripens.
Tomatoes naturally produce ethylene which causes them to ripen. If they are in a bag or container, they will ripen faster because ethylene accumulates in enclosed spaces. So, on a table in a basement with tomatoes not touching each other is idea.
There are several varieties available with a gene that slows down the ripening process. Winterkeeper is an example. Piennolo is another. They can be stored in a humid basement for between 3 and 9 months.