We have DS rearfacing in his boulevard too. My car is a Mercedes R500 which has these brilliant cargo tie downs on the floor that I can tether to, so I lucked out (I did check with a CPS tech and she said she loved those things for RF tethering).
Anyway, in DH's car and when we've rented a car, what we have always had to do is move the front seat as far forward as possible and tether to the metal bar that holds the seat down. The only problem with that is once you do it, you have to get that seat adjusted and you SHOULD NOT move that seat around anymore. What I was told is that anything that does not move with the seat is good for the RF tether, but hopefully a tech or someone with experience with your car can give you the perfect advice
Anyway, in DH's car and when we've rented a car, what we have always had to do is move the front seat as far forward as possible and tether to the metal bar that holds the seat down. The only problem with that is once you do it, you have to get that seat adjusted and you SHOULD NOT move that seat around anymore. What I was told is that anything that does not move with the seat is good for the RF tether, but hopefully a tech or someone with experience with your car can give you the perfect advice
