We're on the verge of ordering a custom mattress from Rocky Mountain Mattress, but they need a "corner radius" measurement for the corner that fits into the Airstream's inner corner. Ours is a 2007 International, and I'm sure they've handled orders from other Airstream owners, but they insist on us providing our own measurement.
Unfortunately, we don't have the trailer right now (it's in Denver at Timeless Travel Trailers) so we aren't able to trace or measure anything in person. We have the width & length measurements, but not a way to describe this corner. I'm attaching an illustration I've adapted from the Airstream website. This includes our NEW l/w measurements, but no information about the curved corner (except for the points where the straight edges start to curve). If anyone can help describe this corner with measurements, or have something you've used to order a custom mattress before, that'd be lovely!