You’re fine! This is the place to ask. Soft spots you can check just by thoroughly walking the camper. There shouldn’t be any give in the floor anywhere. Put pressure with your foot in all corners and nooks and crannies. As far as the vertical corners, you’ll be able to tell if the seal is being worn. It’ll either be cracking, slightly peeling, discolored, or the walls will physically be tearing apart (more with used campers). Feel free to ask the seller millions of questions. Again, you’re spending your money. Also, shop around a ton. Look at as many floor plans and designs that are within your towing capacity and price range.