Well sadly your passenger will have to give up some leg room but I've used these 2 systems so far.
Infant carrier:
http://www.target.com/p/graco-snug-r...Q&gclsrc=aw.ds
Convertible Seat(does not remove):
https://m.toysrus.com/product/index....uctId=58393916 We have 2 of this one and it's been great.