You "could" do that commute on a B200 pharmacy bike with "some" modification to the suspension etc.. What's the point in that??
Buy the right tool for the job, with the least modification needed. To me that tool would be one of the GS12 options, no 2 ways about it.
I did 40 000km on my GS before owning my 990 on which I've done about 14 000km. Sure, the 990 is more fun, especially when it gets rough.
But for long distance commuting, different seasons and conditions you can't fault the GS. When you have to do a trip that will become mundane, and it sounds like it will, you want something that will make it as effortless as possible. With heated grips, height adjustable seat, shaft drive, good wind protection and long service intervals the GS is your answer. Add to that the light handling and tubeless tyres and the decision becomes an easy one...
PS: I fully agree with the statement that you need to go ride all the options properly though.