So we just got a Britax Boulevard...and I've done some research on Car-seat.org, etc., about using the rear-facing tether. We have the seat on the right rear side of our Toyota RAV4 (the center seat position renders all the seatbelts in the back seat unreachable). So anyway, the only way to use the rear tether is to install it "Australian style", with the straps coming over the top of the seat, and wrapped around the back of the seat to the tethor anchor.
Since there is no one "standard" opinion about rear-facing tethers, I was curious about other people's choices regarding whether or not to tether, if you have that option on your carseat. TIA!

Re: Anyone tether a rear-facing carseat?
I wanted to, but I couldn't figure out where to anchor it at the floor behind the passenger seat. We have it on the rear passenger side, as well.
https://www.angelfire.com/wa3/isakswings/ratetherrf.html
Well, I went by the Toyota manual for my car, and the only three tethor anchor points are in the rear of the car.
Are you talking about tethering it to the front passenger seat?
Thanks. I've seen this site, but I have a Britax Diplomat which isn't mentioned here. The manual says rear facing tethering is ok, but there is honestly no spot under my front passenger seat for the D Ring. The seat is automatic and anywhere I might be able to loop the strap through would interfere with the front seat movement.
Yes. It's okay.