Evenflo Triumph Advance
The evenflo triumph advance was not *as* easy to install as any of the above seats, but it was possible to get a good install in all positions I've tried.
Center row:
The Evenflo Triumph Advance installs well FF on the center bench in LATCH or with the vehicle belts.
It can fit next to the RF or FF RA.
I can make the SS1 fit next to it though it's difficult.
The tether is too short & I need to contact Evenflo for the van tether, which is longer. While waiting for the tether extender to come I remembered about tethering to third row seatbelts. I now have it tethered to the male end of the lap only belt in the back row. I tightened the lap belt as far as it would go, attached the tether and then tightened the tether. It works nicely, but renders the third row unusable.
Installation RF in the center row is more difficult, but possible. The big downside is that the harness adjustment knobs are pressed deeply into the seatback and are basicly rendered useless. Getting a FF seat next to it was a small challenge, though possible.
Third row:
In the 3rd row it's possible to get a nice, tight install FF with the vehicle belts; however the seat has a small tilt to it (pic to come).
It's difficult though because the legth of the buckle stalk. One way I found to get a nice tight install was to move the vehicle seat all the way forword (this shortens the buckle stalk) then twist the buckle stalk three times. Then after you lace the seatbelt thru and tighten as much as you can wiggle the restraint. At that point I still had well over an inch of movement. To get rid of it I reclined the vehicle seat, allowed the seatbelt to ratchet in a few more clicks, then I straitened the vehicle seat back to full upright. The install was nice.
RF install was OK too. The vehicle seat does not need to be all the way forword, but the buckle stalk does need a twist. Tightening takes a while, but you will get it. You may need to use a locking clip to prevent the RF tilt that sometimes occurs. I didn't leave the seat installed long enough to know for sure, but it seemed like it wanted to pull up on one side.