Rotopax auxiliary tanks
I had these 1 gallon Rotopax tanks on my Himalayan. They sell mounts specifically for the Himalayan, which is a narrower bike, and they seemed to fit a lot cleaner. There isn't a specific mount for the Tiger so I ordered a couple of universal mounts from Rotopax and found some clamps on Amazon and mounted the tanks.
The water tank could be a necessity but not sure of the need for the addition fuel. The tanks stick out too far and could catch on objects when on trail. If and When the bike gets dropped the additional protuberance could jeopardize the tank. It worked on the Himalayan but not sure it will on the Tiger.
Update: Did not really like how the tanks sat on the engine guard and ultimately took them off. It was worth a try to see how they looked and felt while riding.