The only thing that has ever worked for me (diet or exercise) on the road is accountability - either in the form of having to report back to someone on my activities while away or personal training (with a cancel fee if I no-show).

A couple times I was in a good routine while home and managed to stay on program while away - even to the point where I stopped paying for whatever I was doing at home because figured I could do it myself and save the money (since I was traveling so much) - but I always end up stopping the exercise or going back to poor eating.

If you are paying for a personal trainer at home, why not try and find one in the locations you travel to? Have them come to the hotel or most will have a regular gym. You might even enjoy the variety in workout approaches. Plenty of online sources to find good recommendations and reasonably priced individual trainers. I've started doing this in one of the cities I travel to regularly (have a primary person and a backup if #1 is booked - recommended by a business partner there).