I've attached a drybag straight to my aerobars using cinch straps, which was great for eliminating cable squish. That said, I don't use areobars anymore because I tend to ride with others, and don't spend that much time on flat ground, where they can be used.
If you are looking for just a bit of extra bar space, Problem Solvers makes a beefier mount that holds a typical 22mm bar, and you can even double it up and replace the bar with a wider one if you need more space and strength.
https://problemsolversbike.com/products/accessory-mounts/accessory_mounts_-_27803