The art of (bike) packing?

I’ve got a couple of frame bags - a small Restrap one (2.5l) and a larger expandable Blackburn Outpost one (5.25l/6.95l).

I sometimes use the Restrap frame bag instead of a top tube bag and the Blackburn frame bag for longer trips or if the weather is colder and I need to take extra clothes. The problem with the larger frame bag though is that it means bottle cages can’t be fitted so then you have to use an alternative method of carrying water.

There’s quite a lot of compromise in bikepacking depending on how long you’re going for, the terrain (road or off-road), weather/temperature, whether you’re going to cook or not, which bike you will use

Slight thread hijack ... how do people mount lights on the bars when a bar bag gets in the way? Specifically, the bracket for my Exposure MaxxD doesn't lift the light high enough to give a full beam over the bar bag. I've got the aero spider bracket, so not possible to drop it lower/out of the way.