Welcome to the forum.
I also noticed the sagging at the jack mounting points and I reckon that is because the timber the mounts are bolted onto is rotten through. There is a lot of visible water damage there, including the paint peeling on the inner side panels, the rotten floor and around the roof vent. In
my experience the smallest sign of water damage is just the tip of the ice berg. Typically I would advise anyone looking for a camper to look for the smallest signs of water damage / leaking and not buy if found - yours goes way beyond that. The problem is that because campers have two or more skins (inner and outer), water that gets in travels around between these destroying the timbers BEFORE you see much sign of it appearing on the inside of the camper. I suspect you will find that every inch of timber in that camper is rotten and needs replacing (including the roof, cabover and wings). So that would be not just a huge project (year or two?) but expensive too. I also bet that fridge doesn't work, and they are expensive to replace. It may be justifiable if you were a true fan of that model of camper and wanted to restore one, but if you are just looking for something for your family to camp in I suggest a rethink now before you throw too many $$$ at this.
Assuming you don't want a massive ground-up restoration project, the good thing is that you have only parted with $200 (you could spend that on sealant alone when recaulking a camper). I suggest ripping the camper apart to see the real state of it before you spend a penny more on the project. I suspect it will be a write-off, but in tearing it apart you will 1) obtain some potentially useful spare parts and 2) learn how these campers are built and where the failings are (e.g. identify the bits inside that rot but aren't obvious from the outside). I would then use the knowledge learned from that to hunt around and buy a used camper that is in better condition and will therefore cost you less in the long run. You would have a great advantage over other buyers because you would know exactly what to look out for having stripped a camper already. So think of the money spent buying this camper as a valuable training course to save you many times that amount on the camper that becomes your eventual 'keeper'.
Good luck,
Steve.