My 5 year old son (he'll be 6 in Sept), has gone through a growth spurt, and I realized he's between 64 and 65 lbs. Right at the max in in nautilus. We have a 10-12 hour road trip this weekend, and I don't know what to do. Do I keep him in his harness for the trip, or go ahead and put him in a booster? It looks like I'll be buying a new car seat before then. I'm trying to figure out if I should buy a nautilus again, keep in the harness for the trip, then booster him afterwards. Or should I just buy a booster? Any opinions on the Graco turbobooster with safety surround would be great. Any seat recommendations would be greatly appreciated as well! Thank you!!