As a former Fox owner, I can't speak highly enough about the construction quality. Some of the places we go, there are really rough roads, and always with the earlier TTs, we'd bend or break something inside. 14 years with the Fox and no complaints. This trailer did not sit at home; many, many miles on it, it rode behind 3 different TVs.
Only problems I ever had with it was the loss of the outside shower door due to high winds, and lost the vent flapper for the range exhaust, same winds. We were going past the factory and stopped to get replacement parts, the guy comes back and hands them to me - no charge! He even helped install the outside shower door, showing me how to 'tune' it so I'd never lose another one. That's service.
This fall, we traded our Fox for a Snow River, made by the same outfit: Northwood. I echo the suggestion you go to their Forum and ask all the questions you want. Lots of good, patient people there, a chance to get the opinions of people who own what you're considering.