What you have is a HMO supplement which has special requirements.
What you need if you travel is a PPO supplement whereby you can use any doctor or facility of your choice. What's especially neat about that is that you can go to the best in the country! We have used Transamerica through Good Sam for 10 years and they have always paid everything with no copays. We've had multiple surgeries, including cancer. It works great.
Of course with many new 'rules' coming up in government everything might change for all of us. :(