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I use the Diono Radian RXT (now replaced by the 3RXT, I believe), because of its narrow width. When installed in the center seat, it leaves a usable (although not very comfortable) amount of space for two adults on the sides. There's a discussion on car seats here, Owning Model 3 with 2 kids?, along with some pictures that I posted a while ago.
I recently moved my Radian to the rear right seat. If you allow the car seat to dig into the back of the front passenger headrest, it's possible to move the front passenger seat more than 1" back from its most forward position, contrary to what I mentioned in the other thread. The Diono "angle adjuster" foam block is a must for the Radian when installed rear facing in any seat position.
I had the Diono Radian RXT in my car for a bit on the rear passenger side in rear facing config. I found it blocked the rear window way too much for my comfort so I moved it to my other car and bought a Graco 4Ever for my Model 3. It fits much better in the rear facing config. Both are steel reinforced convertible seats.
If the RXT will be installed in the front facing config, then there should be no issues at all.