Wow can I relate. I travel a ton for work, always on expense account, always taking clients out to eat, etc.
I knew when I started this journey this was going to be the single most difficult area to tackle for me.
I've posted a fair bit about this in the thread I keep up, so I'll direct you there if you want to read details.
Time for a change (story, and ongoing tracker)
But I'm focusing on the following changes that I think are actually workable...
1a. Continue to calorie count everything when I travel even though it involves more guesstimates and is sometimes painful (including the time I had a wrap at a restaurant to later find out it was 900 calories!)
1b. Always have a couple of meal bars, healthy snacks in my briefcase.
2. Any trip longer than 2 days, do my best to get a hotel with a fridge, and go to the grocery store on my way in from the airport.
3. When eating out at a real restaurant, always have a salad to start with (instead of fried or creamy soup), and choose a protein and veggie dish, never do a dish with a carb as the base (like pasta). Always substitute a starchy side for a veggie side.
4. Never ever order pizza or chinese to my hotel room (huge personal weakness)...
5. Always go to the hotel gym before dinner for ANY length of time (I am not a morning exerciser)...
So those are the specific behaviors I've targeted that I've been working on with a good deal of success so far. Still have a long ways to go though.
I've also found the following "casual" line to work well when the inevitable where do you want to eat for lunch discussion happens...
"You know, I'm not picky, but would love something light otherwise I'll be nodding off in here all afternoon."