A bit late to the party but no matter.
I've gone from Vienna to lake Garda so not sure how much overlap of routes there's going to be. But with lots of weight I feel you really can't go too low with gearing. I think I had a 11-34 cassette with a 22-24-44 crankset and would not have frowned at a 11-36 on some of the steeper climbs.
As for not needing the high end of the triple, I feel that coasting forever if boring. Also spinning out on tailwinds sucks. With a 44 big ring that doesn't really happen.
I've tried a wide double for touring and frankly I did not like it. The large jump between big and small chainring is jarring and I felt like I was constantly cross chaining trying to find a proper gear. My road bike has a wide double but with no luggage it doesn't really matter all that much.