I've recently made the foray in to the full suspension world and am wondering where people store their extra water. If I'm running bottles when my frame bag is attached, I can put 2 bottles in stem bags and 1 under the downtube which gives me somewhere between 2L and 3L of water. This is fine when I can refill frequently but if I'm somewhere that there aren't any water resources I will run out pretty quickly. For reference I gulp up around 6-7L of fluids per day while bikepacking (I'm a monster).
I've seen a lot of write ups of people saying they carry an extra 2L or 3L bladder that remains empty until they run into a long stretch without water after which they fill it up. This seems reasonable on my XL hard tail where I have an enormous frame bag which can easily eat up a bladder. However, on my FS bike my frame bag cannot hold a full bladder and the only place to put it seems to be on top of my handlebar roll. I think this would work but it would add significant weight to the bars and I don't think I've ever seen a bikepacking rig with a bladder lashed to the frontroll so I assume that isn't the way to go.
I'd like to avoid wearing my 3L Osprey on my back if possible as my back gets pretty worn out on multi-day trips.