when you are talking 20K + bikes. I think a few bucks spent on rentals is well worth it. Many Harley dealers will give you some store credit for rental fee. BMW stores are usually generous with test rides too. Victory makes a wonderful motor, and for 2 up you really need to ride a Vision, more power and better ground clearance. I know it is unconventional, or as my friend calls it Gay. But damn, riding and not looking at it this is one fine motorcycle.
To go to Alaska, on the 1600 you will encounter road construction and gravel somewhere. It will do it but a GS or a RT will be lighter. Yes, I said RT. No matter what you ride, you need to find some gravel roads and get the feel of it. If I had the money and time 2 up I would pick the RT ,GS or GSA with custom seats. If I was solo and had good lawyers, then I would get the 1600 it is a rocket ship.