Rob,
Don't kick yourself. Assuming everything is intact, you're not really hurting on the deal yet (given what you've said you spent). I came to the same conclusion on my Overlander....that there are two types of old Airstreams.....those with issues and those whose issues have been addressed. After reading some of the posts from members with newer and sometimes brand new units with issues from the factory, I'd rather do it myself. If you think you feel bad now, just think how you'd feel after dropping $40K on a unit with stupid little issues that never should have left the factory. This way, you pay as you go. (And will never approach that number.)
And think of all the fun you'll have!!!!!
My only suggestion at this point is to start at the rear and work your way forward. Deal with the biggest issue first and you can go camping this summer (bathroom will be finished). I haven't searched, but I'm sure you can find 2-part epoxy paint in black, although I'd do some serious praying before I did it!)
There is a '72 Overlander here in Athens gutted, in the process of restoration that you might like to see. He put the new floor in last week, after I fabricated and welded on new rear frame sections (see pics). I'd be more than happy to coach you through this and will save you time and money if you're willing. (It's a lot more fun to help someone else than to work on your own mess.) (Yes, the picture is real, the frame rail was almost completely GONE!)
1. Don't start disassembly until it is securely up on 6 x 6 lumber.
(see my pics) This makes a HUGE difference when working underneath.
2. Accept the fact that you'll have to remove the entire bedroom to get to the bath. There are a couple of screws on the back side of the pocket door which hold the tub that can't be accessed without removing the door. (It's just easier to get everything out of your way)
3. Use ziplock bags and labels to keep track of screws and stuff. It'll save you a lot of time and guesswork in reassembly.
4. Make sure you're on good terms with your neighbors and they understand what you're doing. (if you live on acreage like me, this isn't an issue)
Give me a call