Hi! I am looking to buy some sort of travel car restraint for my LO. LO was ~37" and ~31 pounds at their 30m check up. We will begin use of the restraint when LO is 32mo. The restraint will first be used for 6 days' travel in a rental car. There will be some highway driving during the trip. An adult can sit in the back with LO. Then the restraint will be used for car-pooling three days a week. There will be limited highway driving for car-pool. An adult will not be in the back and there is no need to fit three across for car-pool. LO will use their regular car seat rear-facing until they grow out of it in that position. I know it's best to keep LO rear-facing as long as possible and that there are some potential difficulties with something like Safe Ride 4 Kids or WhizRider, but the compactness and weight of these are incredibly appealing and I'd much prefer either of those to a standard travel car seat. How does age vs size play into safety in the vest-style restraints? How difficult is it to properly install a normal rear-facing travel car seat correctly? I had to have a CPST install our regular car seat. I'd also like to stay away from toxic chemicals as much possible, to the vests appear to win there as well.