Problem solved, sort of.

I never should have had the issue covered in my last post. It could have derailed the entire second book, which is at least half finished. Fortunately, I discovered the solution right in front of me, nestled comfortably among the pages of my first book. Not going to go into details here to avoid spoilers. You really ought to read Atmosphere if you haven't. Anyway, I think I can get away with a few tweaks and one technological advance that is at least plausible.