I was faced with the same concerns about having 2 baby seats in the back of a rs250, and decided to just take the plunge as it would never be the primary car to transport the kids.
After having the car for 3 months now. I can say that I haven't looked back or regretted it. I have a 4 yr old and a two and a half yr old who absolutely love getting into the rs.
My main concerns were picking up and out once they had fallen asleep, but the recaros move so far forward it's no problem at all.
So in short my advice is go out and buy one.