You don't have to use acrylic gesso but it will need to be sized. I prefer dewaxed clear shellac that I make myself. Only a couple coats is required to protect the paper from oil penetration, and no water is required that would distort the paper. Once shellac dries after a few hours it can be lightly sanded and painted on.
You can also size with either hide glue or an acrylic medium. Those involve water so you'd have to stretch the paper first, and you'd need to lay down 3-4 coats, making sure the water has completely evaporated after a couple days before painting.
There are also several brands of commercially prepared papers on the market you can try that are typically treated with an acrylic size. Test them to see if any oil penetrates. If so, add 1-2 more coats of size.
I wouldn't recommend keeping them loose for very long since the dried oil needs something to keep it flat, such as a frame or being mounted to a panel, even just taping them to foamcore for storage.