Re: I would love some Opinions here!!
For price haggling... if it doesn't work and can't be shown to work... it doesn't.
So remove the generator from the equation. As far as the diesel tank, that is probably just the way they set it up. You should be able to set it up (if you want to) however you want. But do you really want to is the question.
The rug needs to be replaced. The kitchen is... survivable. You might want to install a 12" deep section of ventilated (wire rack) linen closet shelving to hold your dishes (dish drainer).
The RV ovens never really "work". Put a pizza stone or a layer of unglazed clay tile on the metal bottom of the oven to even out the temp swings.
David loves to haggle price. He thinks it's a wonderful game. He would start out with $2K. I would start out with $2500.
Suggestion. Pack your cash up in a $2K or $2.5K pack. Then stash a couple hundred in your wallet. Stash another hundred in your pants pocket (Front Left, Front Right). The rest your spouse or someone you trust to carry the cash can hold the rest. Digging the amount over your initial offer should look like you are scraping the bottom of the barrel. Pay with $20's. When you make your first offer. You pull out your $2K pack of 20's and say... "$2000 (or $2500) cash right now." That's a nice wad of money to see in a stack or two. But before you offer, they need to have the title clear and ready to sign over as soon you hand them the cash. Take a good, fully charged battery to crank up the bus with.... and 5 gallons of fresh fuel to get to a gas station.
Yes, there is a lot of the work already done. But a major remodel is very time and money consuming. You never know if you can do a minor cosmetic remodel or a major "down to the studs" remodel until you have started in on it.
On edit... replace the mattresses. You don't want any new pets. As far as that goes... bug bomb the thing 3 times in the space of two weeks. Then bug bomb it two weeks later to kill all the creepy crawlies that have taken up residence.