The first thing that came to mind WAS the
Sunshine Kids Radian...it is the narrowest
convertible seat on the market...my ONLY concern is the 3rd row seatbelts. Let me explain. The buckle portion that comes up from the bight of the seat..if the plastic cover is pretty long, then it likely won't work with the
Radian. The belt path (where the seatbelt goes through to attach the seat to your vehicle) on the
Radian is very low, so SOME vehicles are incompatible with this particular seat. Do you have a USA Baby or a specialty baby store near you that possibly carries the
Radian?
Sunshine Kids has 2
Radians. The
Radian 65 (which will harness to 65lbs) and the
radian 80 (which will harness to 80lbs). There only difference between the 2 is the weight limits--they are both the same shell, so same height.
Another idea is to head to a carseat tech and see if they can help configure some seats for you
congrats!