I'm sure they think about this case more than just when they're in their own car.
If a juror decides to put some books on the seat of their own car to simulate RH's height and looks in the back seat of their car, that would obviously be wrong. Just thinking about the evidence given to them is not wrong.
JMO
Thinking about it-no, wondering about a carseat's proximity in their own car--no, but bending down to pretend pick up something in the passenger well to see what they could see-problem, or adjusting their mirrors- problem, which, Paper Doll, is what I thought you meant. My apologies if I misunderstood.