My twin boys began climbing out of their cribs very earl on. So I bought a mesh crib tent (sold by OneStepAhead. It securely fastens to the top of the crib and has a zipper to open and close it, with a tiny pocket on the outside to tuck the zipper pull into so little finger cannot manipulate it. My boys are very crafty and they never could figure out how to open the tents. They are very high, so toddlers can still stand up and even jump up and down in their cribs without touching the top. It works beautifully. If you can take a crib with you on your next trip, or better yet, rent one where you are going, you can then take the tent with you and attach it. It is easy to install and 100% safe if properly installed. I have rented cribs on trips myself and they will deliver the cribs to the place where you are staying and they will also pick it up when you are finished with it. If you are staying in a hotel, hotels offer cribs as well. Here are links for the crib tent and for crib rentals (and a whole slew of other baby rentals):
Crib Tent http://www.onestepahead.com/catalog/search.jsp?N=0&Nt...
There are hundreds of rental places for cribs and other stuff. So I would just do a google search for one in the area you are visiting.
I hope I was helpful. I have traveled a lot with my twin boys and have tried just about everything (including trying to keep them in pack n plays and laying with them until they fall asleep. At one point, I switched to a small tent with blow-up kiddie beds for each of them. I hung a battery powered night lite in the top of the tent and locked the tent zippers on the outside. It was their own little portable bedroom and they LOVED it. I even played soft music outside the tent to soothe them. But, of course, you have to be somewhere a tent will fit (large living room or bedroom). It worked for me most places, and where it didn't... I rented cribs. My boys were doing summersaults from one pack n play to the other and cracking themselves up. It was very frustrating.