Some thoughts on various aspects of the topic:
Seems to me that the insulation issue with soft sides need only copy the better sleeping bag batten designs and incorporate some insulation. How much would be a trade off with how much collapsed room could be given to it.
Alternately the insulation could be a 'curtain', again copying the better bag batten design(s), that is independent of the actual soft side and is either fastened in place when needed or stowed out of the way (rolled up ala tent doors?).The only illustration that I found with a short search:
With a hard sided pop-top, could there not be a flexible boot be attached such that either a wiper type seal or a labyrinth type seal would be redundant?
Having seen pictures of what a western Sierras black bear can do to a car when in search of food, I think even the hard walls of a Unicat etc. impart a very false sense of security.
I used to swerve around my hallucinations, now I drive right through them.