As I mentioned earlier, look for leaks around the bunks. That is common. Also, just look around for anything loose, like cabinet doors. But, the floor plan looks nice.
As far as European ratings, yes they are higher. Heck, my Jeep is rated at something like 7500lbs across the puddle. But, IMO, the 4500lb, 22ft Roo is putting the vehicle at it's limits. I had to do some serious mods to help keep it cool, and tune the engine and transmission shift points. I would love to know where they get the ratings. But, at least my hitch is rated at 750/7500.