If you get the bag I told you about, please post some comments on it. I'm interested, but would like to hear what you think of it after using it first hand.
Kathy's Bar Bag
Would this work? I have this bag and use it as a small tail bag on my GS. Not sure how it would fit on the RT.
Another option is Bags For Bikes. Karla custom made this bag for my Norge based on the measurements I sent to her. Very high quality, reasonably priced and fast turn around time. Perhaps she can design something specific for you. bags for bikes