Extended Rear Facing: Nine Car Seats that RF up to 50 Pounds
Here are the seats, all available on Amazon.com (affiliate links). Many of the seats are available through Prime so you will get your seat in two days.
Dana Lange also works for Modern Natural Baby in Ferndale where they provide FREE car seat inspections with the purchase of any seat. Currently they carry the Clek and Diono seats mentioned above. Support local business and get a free car seat check! Awesome!