This is one of the problems with gambling. But to be honest - it is the gambler problem, not the casino`s. If the gambler can`t stop - he mustn`t visit the casino while travelling. He can lose all his money and spend a lot of time in casino. So the result can be that such gambler can broke his vacation plan and late on the train/airplane. If he lost all his money - it can become a problem.
It's not that easy to stop a habit especially something which is addictive. But the idea is there, it solely depends on the player whether he would be too hooked up in gambling activity or not. It is also not losing which is the concern here I guess, but how it affects an individual. Everything which is too much is bad. There's no relationship with travelling and gambling; but having no alternative activity is. I understand OP's perspective a little, if he just enjoy playing then that won't be a problem but if it pushes him to his/her limit in different factors, things should be really changed while there's time. What I mean with diversion is trying to appreciate what are the other things around you exept for the behavior or activity you are trying to limit or avoid.
In my opinion - if there is a problem with the gambling - the best way is to avoid all casinos, both online and offline. It is difficult, you`re right, but it can become a problem not only for gambler but for his family too. And in offline casino gambling much interesting, so the risk to break the vacation due to such a visit - higher. It is better to replace gambling with any other habit which gives positive emotions if it is impossible to control it.