The only way to use saddle bags and be able to access them is if they are on a horse you have tamed and are actively leading with a rope.
Reference
https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://steamcommunity.com/app/366220/discussions/0/3288067088111905420/&ved=2ahUKEwj1lYnqg4SHAxXYRDABHZaVCJ0Qjjh6BAgTEAE&usg=AOvVaw3D0NQYyhaDB050WWYL8iVT