My son went through the same thing -- he was a great sleeper at home but awful when out of his element. It took several attempts but we were just consistent in our response to him and he finally learned to sleep away from home, the same way he did at home. That said, he's not a climber, so I didn't have to worry about that while he was learning.
Could you try a pack and play with a screen topper, like the Graco Sport or Phil & Ted's Traveller Cot? For the Phil & Ted's specifically, he might get annoyed that he can't stand up in the crib, but he also won't have a way to get out. For the Graco Sport, I don't think they sell these anymore but I've seen them on Craigslist and in consignment stores. The Graco canopy is really tall and it's a huge hexagonal play yard, so it's great for sleep but could be a pain for travel and I've heard is impossible to find sheets.
You could practice at home to let him get familiar with the canopy. Then go to a friends house (maybe without other children around, so he's not distracted by playing) and tell him he's going to nap while you there, then give it a shot.
Definitely keep the routine the same. For us that means ensuring he has a fan or some other white noise in the room. He's used to this and can't handle thinking that "they're having fun in the other room without me!" If he can't hear what's happening elsewhere, he just shuts off and goes to sleep. Maybe your son is experiencing something similar? He's probably just wound up from the excitement of travel and when you respond differently than at home, he quickly learns he can get back to the action by crying or climbing out of the crib.
I hope this helps, and good luck!
Oh, and just for the record, my son is now two years old and we still haven't tried camping. He's just too light a sleeper and really needs his sleep to function properly. We're going to try to find a battery operated white noise machine and try camping this summer, but I'm doubtful he'll be able to sleep if he can hear all the noise around the campfire or from other campsites...