just my thoughts here, as for riding a Gold Wing, I ride a 1500 with a sidecar and I added driver floor boards and highway boards and can easily stretch out while running down the road
also I just recently bought a Yamaha Royal Star venture for my wife, it has an outrigger kit on it, it is water cooled and is a 1300 so it has decent power and handles nice.
I will say that even though it's water cooled that V twin engine being exposed and the pipes dropping off the side like it does will generate a good bit more heat than my Wing does
But it's not as bad as I expected it to be. Being here in the south we get some hot days as well so I feel you pain
Good luck hopefully you will find just what your looking for