Your work schedule sounds punishing (lots of commuting and travel). Do you move around at work at all? If so, you might be surprised at how much walking you are already doing. Perhaps you can walk faster (wear running shoes and carry dress shoes in your briefcase or whatever) around the office and to and from the train. Can you take some time at lunch and walk or run? Is there a gym near the office? Although, frankly, I am not a great fan of gyms...so much effort to get there. And then all those buff people in spandex

Resistance training can certainly be done in a hotel room with light weights. Those hotel carpets are also usually thick enough to allow some "mat" work like ab crunches without the need for a toted-from-home exercise mat. Hotels also often contain a pool for guests to use. Water-walking (sort of jogging through the water) and swimming laps are great ways to de-stress.

Even running on the spot in front of the tv helps! It's just like a tread mill but cheaper! (Well, not really "just like", but you know what I mean).

Good luck!