Airstreams aren't perfect. There are a few other great trailers out there. But, if you like me just want one... well have a reasonable PLAN and then DO IT.
I try not to be judgmental, but it gets me upset to see people who "can't afford" health insurance for their kids, but spend $50 per week at Starbucks, and have $8,000 worth of designer shoes and purses. It ticks me off to have neighbors who "collect" stuff to the point that they are actually hoarders.
But if you generally have all of your ducks in a row financially (which if you know you "can't afford" an Airstream, you probably do), then...
... then I have contrary advice.
You get one LIFE. This one is NOT a dress rehearsal.
It will be over sooner than you know, and what happens afterwards is really unprovable. So just in case this really IS it - get and enjoy something that will make your family happy.
You don't have to buy a brand new one, or spend $40K on restoring an old one, there is a big happy medium of 2 to 5 year old ones, with many available because the owner is moving on up to a larger one. Before you buy see as many in real life as possible (the reality is so much different from the floor plans and the photos that it's amazing), take your time, don't grab the first one you see... and go for it.
I don't LIKE owing money, but rates are still pretty low, and if you get a used one from a dealer you can get 4% easily. If you use it every weekend and as a guest house (or to hide from the kids for an hour)... then justify every great memory at $10K... you're Airstream is going to have a lot faster return on investment than a shrink, a marriage counselor or a child psychologist! A happy childhood is a great bulwark against life's ups and downs ... and I'm in my second childhood proving that!
It's a guilty little pleasure! And one that isn't illegal, immoral, or fattening!
Today is a gift, that's why they call it the present.