FWIW, on my most recent tours I have used neither panniers nor typical bikepacking bags. I went with alternate setups using a bar roll (or in one case a big handlebar bag) and stuff sacks strapped on the rear rack. If you pack light and split the gear between the bar roll (maybe 3 or 4 pounds), rear rack (maybe 5 or 6 pounds), and a little backpack (maybe 3 or 4 pounds). Those numbers are just the gear. Some food gets squeezed in where it will fit. Water is in bottles on the frame and supplemented as needed depending on resupply access. Sometimes I need to carry a few bottles in the backpack.
Not often, but now and then there may be a day when I need to carry water for a 24 hour period. In that case I load the backpack pretty heavy. I don't like it but the weight goes down as the day goes on.