Material suitable for making 18th Century panniers?

Im making an 18th century court gown, and I’m halfway through creating it. The length on either side is about 2 feet, and width about 1 foot. The panniers I’ve got at the moment are two fabric bags stuffed with loads of bubble wrap/off-cut material (made by me obviously lol), but they keep sagging downwards, so I really need the name of a material to construct the panniers with which can take the wait of heavy chenille fabric, but at the same time bee light and easy to work with