I was out of the country for 3 months before I started NROL. Most of my time was spent in cramped hotel rooms. But I tried to do as much as I could in the hotel room. I did as many different types of push-ups as I could. Regular, diamond, elevated, decline, one arm on a block or something. Whatever. I did bodyweight squats, jumps, burpees. I made up my own short circuits. It wasn't the best, but it definitely was a workout.
I would also try to look for parks, where there was exercise equipment. Like bars where you can do chin-ups, parallel bars for dips, etc.
There's always tabata too. You can do that with body weight squats, and it only takes 4 minutes, and you don't need much room.
TESTOSTERONE NATION
When you are travelling, the excuses to not work out become much easier, so it's good to have a plan, and try to stick to it.