There's nothing wrong with all the bikes mentioned, but I would hate to be the rear seat passenger on a WR or DRZ - we're talking 37" seat heights. For the purpose you describe, I would think smaller is better - especially in places outside N. America. Heck, I think the scooter is a pretty good idea but you might as well get a TW200 for about the same price. An XT225/250 or DR200 would also be an idea.
But if your MOG gets stranded somewhere really rutted and rocky - "Rubicon-esque", I would think the TW is the best bike to get you back to civilization. Might not get there fast, but it would get there. Remember, some terrain is a lot easier in a 4wd than with a motorcycle. A lower bike that when needed you could push/carry/help over obstacles will get you farther. You may find yourself on trails that you just don't want to try with a KLR650 two up. And since your not intending to go 2 up on the freeway, who needs a 650 anyway. Hell, an old Honda Trail70 will probably get you out of more places than a 650 dual sport. Won't get you out fast, but it will get you out even if the two of you need to help it along the way.
I'm not an expert, but for what you describe I can't think of a more perfect fit than a TW200.