DH usually keeps the Radian installed with the seatbelt in the center of his Acura TL. When he has to install the Radian RF outboard, he uses LATCH. He says he's never had a problem getting the installation tight with the RF boot and the boot has never interfered with the anchors. His LATCH anchors sit really far back in the seat bight. He has to dig way into the seat bight to get the alligator clips to "latch" onto the LATCH anchors, so I'm not sure if that would make any difference.
But anyway, what he does with a RF outboard installation is that he pushes the front seat all the way forward. Then he installs the Radian RF with the boot. Then he sits in the front seat and, for lack of a better word, jams the front seat all the way back into the seatshell of the Radian. The RF boot still stays flush on the seat against the seat bight, and the bottom of the Radian remain in contact with the vehicle seat, but you get less of a 45 degree angle. The Radian is like the Britax seats in that it can be braced against the front seats. DH also connects up the RF tether. But, he claims he really doesn't have to because with the outboard LATCH installation and the bracing against the front seat, he can rock the entire car when he tries to wiggle the Radian.