If you can brace that should solve the problem. IME, it keeps reclining as the child sits in it over time. This actually happens a bit with all seats, but it's the fact that the radian can't be installed much more upright to being with that is the big issue. When you install it with the the foot back from the seat back to get it more upright, it slides towards the seat. Other seats don't see to do that. My '09 prohibits touching, though. It's in the airbag section, not the child restraint section, so go read that section carefully to be sure. Here it is in the '05 manual: http://www.car-seat.org/showthread.php?p=641190 so you know what to look for. If it's in '05 and '09 I'd bet you anything it's in the '08.
The CA installs like a dream in the Sienna. The MR is great too, but not for taller kids!
The CA installs like a dream in the Sienna. The MR is great too, but not for taller kids!