I completely agree with getting the higher weight
convertible carseats that hold 65+ lbs. I have a
Britax Marathon and was able to fit it in my 2-door truck
rear-facing with very few issues. Good job with picking the
Safeseat! This means that your second little one can ride in that until your first angel is past the 33-35lb
RF limit and you can transfer seats (as long as they arent expired) to a
FF seat like the
Britax Regent for baby #1.
Babies R Us is more than happy to have an employee take any of their carseats out to your vehicle so that you can try their fit, I recommend you do this! Good luck!