I tried installing a Radian in my van, before I bought one. I think it installed pretty well after a few tries. Unfortunately, I didn't attach the RF tether, or put Sofi in it.
I bought a pretty pink Radian. I installed it, attached the tether, and put Sofi in. Attaching the tether reclined it a little more, and so did Sofi's weight :( I got tips from others online that had successfully install it in the center seat in this van, and it just wouldn't work for me :( I'd pretty much given up :(
Then, I got a message from another carseat crazy friend. She had a different way of installing the seat. So, I went out today and gave it a try. I reclined the vehicle seatback all the way, and put the base of the Radian forward of the hump on the van seat (there is a hump at the seatbite that covers the lower anchors). Didn't think that would work at all, there was a ton of space between the seatback and the Radian (even with the seatback put back up). I pulled and pulled the LATCH strap to tighten. It was still too loose :( I put the strap through the belt path to pull at a different angle, and it wouldn't tighten :( I had my husband pull, and it wouldn't tighten :( I took it out of the belt path to pull from the top again, I knelt on the Radian and bounced a little and pulled alot. And It got tight! I put the vehicle seatback up again, and voila! I attached the tether and had Sofi climb in. The seat reclined just a tad more, but not too much :)
I WIN! Sofi now has a new carseat :) She looks like she has less legroom than in the Titan, but alot more room to grow heightwise.