There are various form factors of frame bags - everything from full frame to just a wedge for one of the triangle corners to a sliver across the top. I typically use a sliver or half frame when doing multi day rides. Getting bottle in/out isn't too bad. You may want sideload cages though. Last year when I did my 2-day ride up to NH managed with just a frame bag and bar bag. (I was credit card touring)

https://www.youtube.com/watch?v=Gysv9XUehSc
https://youtu.be/NjdIpMUQsPg?si=BurYnyNlFJ36TWR9