I have been waiting to purchase a Vivo for DS to use in DH's car (and in my father's car). Right now we move a Safeguard GO between those two cars for DS. DH has been commenting that DS falls asleep and his head goes forward and doesn't seem supported at all by the head support and wings on the GO. FWIW, DH had to get another car and the seatback is really straight (2008 elantra). I wonder if that contributes to the headflop? Plus, this January we are moving DD to the GO in DH's car (her MA will expire), do DS will need something else anyway.
DS is roughly 40 lbs, 44 inches and is almost 5 1/2. What type of support does the Vivo offer for a sleeping child, if any? Would a turbo booster (HB version) be any better or worse? Are those my best options for a skinny kid as far as HBB's go?