I recently broke my wrist and will need to wear a cast or splint for the next 6 weeks or so, which means I won't be able to drive for at least that long. I have a 3-year-old (almost 4) who usually rides in a Britax Marathon 70. He is about 36 pounds but has outgrown the Marathon's RF height limit, so he rides FF. While I am recovering, we can take buses or trains for some trips, but for trips out of range of public transportation, we will have to take taxis or carpool. I am looking for a seat that is very lightweight and portable, and can be easily installed in a taxi or friend's car, since I'll have to either install it one-handed or explain to someone else how to install it. I am hoping to not spend too much, since this is a short-term situation. Thank you for any suggestions.