If you haven't already, I'd go back and look through the forums devoted to the subject. You needn't look just at Argosy's.
From my point of view, the big structural problems to check out are floor rot and frame separation. Keyword searches will net you a lot of info on both, and the time and cost for repair. We purchased our TT with the entrance area already repaired, and a new floor laid down, but the POs ignored the very rear of the trailer (behind the toilet). Either water from the dump hoses worked it's way to that area, or a leaking valve on the toilet allowed water to congregate. Since the majority of the trailer is sound, we'll tackle that this winter.
I love our Argosy - it really stands out from all the box TTs you see!