The double pane concept was implemented for several years only to be abandoned by Airstream Manufacturing. There were many more Airstreams made with single pane than double pane.
With that being said, you stand to lose so little, (insulation), by removing the inner pane. It is recommended to remove the inner pane many more times than recommended not.
Plain english: Brake the inner pane and you will be very happy with the results.
Use a automatic center punch, one of those spring loaded jokers. tape plastic bag under the frame and hold the bag open when you cycle the automatic punch. glass will fall into the bag.
Very easy to do.