an observation over the years:
riders who tend to "soft pedal" and or coast a lot and or generally put out much less pedalling power consistently, tend to experience the concerns expressed by this person--who hasn't actually gone touring yet.
When we pedal a touring bike all day, which is always going to be 20, 30, 40lbs heavier than an unloaded bike, we simply naturally are having to put out more effort to bike along.
Greatbasin--in simple terms, when we consistently put more effort into pedalling, more leg effort--we take pressure OFF our bum and our hands. The position that you think is uncomfortable (your Surly photo example) is actually more efficient for all day riding for finding that sweet spot of balance of pressure between the three contact points--hands, seat and pedals.
the more we ride, the stronger we are legs wise and core wise, and ones "sweet spot" of positioning of the three contact points is where one can be most efficient for forward motion and body comfort.
in the end, you just gottta ride a lot, and you'll see what works for you, but that position will change over time the more you ride most likely as you get stronger--but go with what feels ok and adjust--no amount of "theorizing" without lots of riding will change that, other than an internet forum experience.
enjoy getting out on a bike regularly