Can I use a narrowide chainring on a double rings crankset?

There would be a 50% chance for a narrow chain link to sit onto a wide tooth during a transition from the small ring to the big ring. This would result in chain misplacement and imminent failure under load [thanks to @mattnz for figuring that out].

Narrow-wide is all about chain retention, while what one needs in a front double by definition is chain derailing easily and reliably.

My suggestion is to have a proper double chainrings. Given that you'll be touring, you'll need to consider possibility of repairs, and finding a new regular chainring would be much easier than a fancy narrow-wide one.

You can also have two front chainrings but no front derailleur. In this case, gear switching happens by hand: stop, throw the chain from one ring to another, and move on. Provided that you do not plan to use the granny gear often, it may turn out to be a viable option.

I would like to thank all you who helped me during this research. I have now cycled around 7.000 km and I can tell you that as soon as you get to the big mountains in Slovenia and the Alps changing the font chain-ring "by hand" is not anymore a viable solution. It is as well very impractical to get off while you climb a big mountain, as well as holding a touring bike while changing the ring... As soon as I reached Slovenia I started looking for a normal chain-ring and a front mech (since I had already Shimano drop bars shifters). I have now cycled several months using the double on the front and being able to shift from my bars. Much better :)