What I see is basically unsalvageable. Presuming the sky was blue, a filter SHOULD have been used. I wouldn't flash the paper--that would only look like a fogged print. Making a masking negative would do the trick better than any burn/dodge. That might get your sky back, unless it's so far over the curve shoulder there's nothing there.
Quite the opposite, flashing is ideal for images like this. Flashing paper doesn't look remotely like a fogged print either, you need to see the technique in use.