You should consider this tank bag if you are looking for a smaller, less intrusive tank bag than BMW's K1200S standard bag (- Part number: 71607691516) and BMW's K1200S tank bag without Navigator (- Part number: 71607691391):
Consider BMW's tank pouch for the K1200LT.
It is perfect for day trips, handy for storing your wallet, cell phone, house keys, and other items you want at easy access. It has a map pocket and rain fly and is very easy to take on and off. With minimal mods/ Velcro you can fit it to the Airbox/ Battery cover.
BMW of Santa Cruz has it as Part number: 71602342670 for $95.00.
I have both bags - BMW's K1200S tank bag without Navigator and the K1200LT tank pouch. I find the K1200S tank bag interfers with my arms and chest when I am riding. I've modified the bag mounts to move the bag forward and out of the way. But it is not a perfect solution.
The K1200LT tank pouch is perfect. It does not interfer with my riding. It is large enough to carry my cell phone, sun glasses, Plexus, first-aid kit with room to spare. And I can tuck my Garmin ETrex Vista in the map pocket. A rain fly is provided that gives full visability to the map pocket and makes it waterproof.
Its definately worth checking out.