If you study 19th century landscape photography you'll see a very similar over-exposed sky affect. This is because, like with paper negatives, such emulsions were sensitive mainly to blue and UV, of which sky light predominates.
For my purposes of creating landscape images with paper negatives, I ignore sky detail as part of the composition, assuming it will be washed out to a pure white tone. This is how 19th century landscape photographers composed; it's just a different aesthetic. It wasn't until the likes of the F64 Group and Ansel Adams that a heavily red-filtered, dark-toned sky became the accepted norm in landscape photography, since by then emulsions were panchromatic.
If you want to experiment with getting "normal" sky detail with paper negatives, just drastically under-expose the image; the sky will look normal but the landscape will be very much under-exposed, so much as to nearly be rendered as a silhouette. This is because paper emulsions are predominately sensitive to blue and UV.
Another method for getting some sky detail, especially in the corners, is with ultra-wide angle pinhole cameras, where the exposure fall-off in the corners and edges is sufficient to render some detail visible.
But for normal glass lenses, I just accept the 19th century tonal representation as part of the charm of paper negatives, and compose accordingly. Yes, preflashing helps, mainly in rendered more shadow detail, but not really in regaining sky detail.
~Joe