I often use the V-necked sweater to dress up a casual look, especially when I travel. Is it too 'faux' to layer a crew-necked T-shirt under a V-necked one?"
It's not at all faux. It's just really boring. How is a V-neck T-shirt going to dress anything up? A T-shirt is a T-shirt, and a V-necked one is no more formal than a crew. And if a V-neck is more interesting than a crew, why not wear it on its own? Because it's too revealing? Wow, you really are a guy.
The layered-T-shirt look looks really frat-boy to me. It expresses extreme sartorial caution; it means golf or poker nights with the guys. In a word – it represents the boy's life or, as you say, uncomfortable long-distance travel.
Sure, the days when people thought it proper to dress up to travel are long gone. I remember as a child being pushed into a tweed jacket and tie for long transatlantic flights. I never questioned why such discomfort was necessary. I just knew it was because my dad said it was.
Years later, I realized that the practice was a sure sign of being lower-middle-class. The rich had no such obsession with respectability. It's just as well that useless constriction during travel is passé. Air travel has grown generally more uncomfortable than it ever was; there's no sense in subjecting your best clothes to the pretzelled sweat-ball your body will become. And yet many of us have a sense that the extreme relaxation of travel outfits has gone a little too far. When half the adults in your cabin are wearing some variation on pyjamas, you develop a sense that the world is regressing to an infantile state.
David Sedaris put this best in his last collection of essays: "I should be used to the way Americans dress when travelling, yet it still manages to amaze me. It's as if the person next to you had been washing shoe polish off a pig, then suddenly threw down his sponge saying, '[Expletive] this! I'm going to Los Angeles!' "
Your travel outfit doesn't sound nearly that bad, but still, it doesn't need to be so square. A nice heavy cotton, unfaded T-shirt – crew or V – can be an elegant accessory to a blazer or cotton jacket. If the blazer is too fancy for your flight (maybe you're going to the Serengeti?), and you're worried that a single shirt might not be warm enough, have you considered a trim Eisenhower jacket? Jackets, with their lightly structured shoulders, are always more flattering than sweaters.