Are you sure it is healthy to have her rear facing at that age. I agree rear facing is best for as long as possible. However, I would be very concerned about legs being folded up like that. That can not be good for the development of the spine, especially on longer trips. Also, you mentioned the only requirement for rear facing is the 1" from the top of the seat. My seats (Graco Comfort Sport and Evenflo Symphony) also have a weight restriction on rear facing (35# max)
Absolutely sure.
In Sweden they routinely rear face until 4-6 years, and have since the 1960s. And their traffic record shows the lack of kids dying that we can only wish we'll have some day.
Her legs were straight out there, not folded. She was always far more comfortable with her legs rear facing than forward. Also, there are fewer chances of leg injuries rear facing since her legs cannot gain momentum to go flying forward (nor her arms, in addition to her spine).
She's sitting properly, just as she would be forward facing, and her spine is straight and braced, so I cannot see how it's dangerous for spinal development. If you have any links to show where you've seen it's a concern I'd love to see them.
You're right, I didn't mention the weight limits rear facing. The OP's son was nowhere near them, and in her case she was concerned because she'd been told he was at the height limits by having his feet touch the back. So I discussed when a seat is really outgrown by height, which has nothing to do with the legs. If she'd been told that she had to turn him because he was 20 pounds then I would have mentioned the weight limit, but probably not the height. But you're absolutely correct, it's the weight limit (35 pounds in the case of her Boulevard) or 1" of hard shell above the head (with the exception of the Safety 1st Complete Air, which allows the head to the top of the headrest). In the case of my daughter's picture above, she was 32.5 pounds in a 33 pound rear facing seat.
Your Comfortsport only goes to 30 pounds rear facing, not 35. Your Symphony goes to 35.
And for the record, I'm not at all opposed to five year olds rear facing, it doesn't concern me about spinal development (which is also nearly ossified by that age, btw, I'd be far more concerned about spinal development in the 0-2 year old range when the bones are ossifying), but she didn't ride like that normally at five. At five she was forward facing and occasionally in a booster. She was rear facing because my mother and brother were in town and we needed to fit the two of them in the backseat with her, and the only way to give them shoulder room enough was to use the Radian rear facing. She rode rear facing for about a week, then I turned her forward again.
Wendy