Yep, first advice is that unless you have a good friend working at the RV place, don't bring this thing anywhere near it. Chances are they'd just laugh at you anyway. RV shops do business making overpriced repairs to functioning units, not working on junkers.
Not to call this one a junker...but by RV industry standards, that's what you've got.
You'll need to find the extent of the water damage. Could be that it'll need to be fully gutted, could be it won't. Start seeing what appliances work. If you do need to gut it, knowing before you start whether the
fridge, stove,
furnace and
electrical system work will help you plan finances and all that. Once it's all pulled out it's a lot harder to test.