Hopefully these photos with answer some of your questions:
Bag mounted forward...one side
Closeup of the same side
Now bag(s) moved towards the rear of the bike...side shot
top view (towards the rear)
I'm sure you could move this further back if needed. My goal is to keep the height of the bag close to the height of the seat. For reference - I had the edge of the GL bag just cover the Berg logo on the seat.
Some details of the waterproof liner:
Velcro detached showing access
Same system as US-5
mounting points for reference (I had the camera out...might as well)
Shot of the back (have not ridden off road with the tool tube, but Cyborg has had great results)
Photo showing how I utilized the other tie down to strap stuff to the back (figure-9 and some rope). My last trip I used this to strap down a ground tarp, trash and the US-5 (before I bolted it to the bike).
The end...hope that helps