Okay, this is not exactly Vintage Kin but that seemed as good a place as any to post this thread.
On another forum owned by AndyR I came across this post:
RV's---never again - Page 2 - Early Retirement & Financial Independence Community
If the link doesn't take you there directly, look for post number 21 on page 2.
This person is designing their own 5th wheel, made of aluminum, they're avoiding any holes in the roof. The project looks very interesting. I hope the person has time to post more pictures as the project progresses.
It's not an Airstream and it's not vintage but it is very cool in my mind.