It works better if you keep them from touching. Any kind of paper should work. If you can keep them separated in the cardboard box it might work. I’ve known some people have keep them in sawdust but I’ve never tried it. Do you have any paper bags? That would work. There is always green tomato salsa but I’m thinking you don’t have the time to process and can.I always wait till they start to turn to bring them in, but I have so many super green ones that I want to try to ripen. Do you think in a cardboard box will work? I don't have any newspaper.
I bring the fig in after a few good frosts when all the leaves have fallen off. Then it goes upstairs, we dont dont heat up there. I cover it with a sheet & leave it till spring, except for a couple waterings.