Car seat for giant toddler

Rachel

So I’m looking for a car seat for grandma’s car for my giant 2 year old. He’s 40 pounds and 37.5 inches tall. My fiancé and I both have the Graco Extend2Fit and love that he can still be rear facing but my thought is that he’s almost at the max weight for rear facing in this seat... should we just get him a 3-in-one seat that is around the same price instead since it will last longer in the long run?

Any recommendations? Something that is not overly expensive, like around $150 or less?