I didn't read all 4 pages of this thread and I don't want to comment on the 10 year rule.
But, I have a 22 year old TT I did not purchase it new. I've had it for about 4 years. It is obvious that not that many things have gone wrong. I did have to put a Dinosaur board in the fridge. I replaced the original tires when I bought it. And, the awning is in sorry shape. I don't use the awning often so I don't care.
The curtains need to be replaced , and I really should have the roof coated. But, I store the TT inside a shed, I'm just a weekend camper, and the TT is so old it's not worth the effort.
Those are the only problems that I've had.