I think this is an interesting topic and I think it's good for other buyers (and sellers) to understand the other side. I don't think anyone's trying to bash you, I think they are just seeing it as a big reg flag for the buyer.
If a buyer lets you stay in their RV alone for a night, who knows what they will wake up to. You could spend your time yanking cabinet doors off, pulling paneling off, etc. You could wake up in the middle of the night, accidentally hit a stove knob on the way to the bathroom and fill the RV with propane. You could steal an appliance, tv, etc. from the RV during the night and drive away. You could just make a big mess and walk away in the morning.
The contract you offered doesn't protect the seller from any of the above. The only one it protects is you - you don't have to buy the RV for any reason you desire after you take up a whole lot of the seller's time.
On the buyer's side, I completely understand the importance of being able to check everything out before buying. I think sellers should be required to hook up water and electrical for potential buyers. If I were selling, I would plug in the RV and make sure the fridge was turned on so that potential buyers would know it worked on electrical or propane at least. Fridges are difficult because it takes so long for them to get cold. It's hard to verify that the plugging into electrical was the reason the fridge is cold (they could have turned on the propane to cool it, then turned it off right before you got there). But, if it's cold, you know it runs on one or the other.
When I bought my RV from a used dealer, they were being jerks about hooking anything up. I was OK with the water because there was water in the fresh tank - so I could run the faucets and check for leaks, and I could light the water heater to ensure I got hot water. Stove was an easy check. With the fridge, it was a lot harder. I got them to agree that if I contacted them within 48 hours of purchase to tell them the fridge didn't work, that they would switch it out with the working fridge in my TT that I was trading in. I figured if they agreed to the deal, that the fridge most likely worked - and they had to come pick up the TT the following week, so I could witness the entire fridge exchange. The RV's fridge worked perfect.