Just thinking through seats, would love some thoughts...

We had 2 nautiluses for our girls. But they were leaving bruises on their backs. My original intent was to just get 2 more nautis, because Miriam believes I just got defective seats. But if I have that problem again, I'm out the money. DD1 is tall and has a long torso. She is over the third slots by just a bit in the nauti. So I'm thinking we should just get her a regent. She has SPD and cannot sit still and has very little impulse control. I would like her harnessed as long as humanly possible. So the regent is probably my best option for her. I've been wondering if the frontier is the better option though, as I've heard that you lose so much height on install with the regent that it's almost the same. There is nowhere around here that sells the regent. For my dd2, I was considering getting the Daisy nautilus and trying it out and returning it if we have a problem. She is smallish average and will not outgrow this seat fast. But, I'm thinking maybe I should get 1 regent 1 frontier so that I can shift seats around as needed between the 2. I guess my only option is to order a regent and then try a frontier in the car and see which is better? We don't have a van right now, so I'm not sure what vehicle it will be going in yet, but it will be a minivan. So, please give me your opinions.

My DDs are
DD1=4.5, 42 poounds, 42 inches, torso is either 16 1/2 or 17 inches (very wiggly)
DD2=2.75, 32 pounds, 36 inches, torso is about 13 1/4 inches

When we were debating this for our 3yr, 42# ds. He was outgrowing the bv by height. The naut was to narrow for him. I decided on the frontier. The slots were pretty equal with having to use the bar in the regent. And the frontier is good for 9 years and would have been his last seat.

We ended up with my friends husky that was sitting around loosing life.