For multi day tours (road/path/gravel, no real mountain biking) credit card style (no camping/cooking) I found this set up with a small frame bag let me move away from panniers. I had to switch to side load water bottle holders and use my smaller water bottles but on the riding/tours I do that is not an issue. I can add a third water bottle under the down tube but it gets filthy very quickly! If I really need, there are fork brazeons where I could carry more water.

The top tube hanging frame bag carries heavy tools and cable/lock on one side, meal bars on the other. On tours where I'm putting the bike on a train (like Amtrak) this approach has worked out much better than my old pannier setup.