Didn't realize just how long it had been since I posted this - sorry for not responding sooner! I finally took the plunge and bought my TC at the end of December, and I just today got around to taking out the rear seats and creating the Puppalace in the back. I've been using a smaller 30" crate for the last couple of months, bungee-corded in place on the laid-flat seats, but now they'll have much more room and available height, while still being safe (the new 42" crate is also bungee-corded in place, attached to the tie-downs in the floor).
I'd never even heard of or thought of the idea of pets preventing medics from getting to their owner in the event of an accident and having to be restrained, or even killed. Good to know, but just the thought of it also completely freaked me out - thanks for that...