Many years ago when I first decided to go with a pop-up camper I looked at Viking. I found them to be well made and well appointed. Back then I looked at other manufacturers that are now no longer making pop-ups, Such as Texsun and Sunlite. I felt Viking was the best of the lot and was surprised when they folded(pun intended).
As with any camper, hard side or soft side, check for water stains that would indicate a leak. Since Vikings are no longer being manufactured take a hard look at the canvas. Look for ware at the four corners ,top and bottom and at the crease marks where it folds up. A replacement canvas may be hard to find.
Hope this helps.
Mike
Thanks Mike good stuff to think about esp the canvas replacement , got stood up tonight no call hopefully he didn't sell it on me ,D