Travel car seat advice needed for 5-yr-old. Lots of highway driving.

We're flying to a vacation and then there will be hours of highway driving. Would do you suggest for a travel car seat? Bubblebum Booster? Safety travel vest thing? Our actual car seat? This is for a 5-year-old who is 36lb 44". Ideally I don't want a huge heavy solution (like our actual carseat) but I'm totally willing to do that.Edit -- P.S. I don't care about her being able to fall asleep in it. She'll be glued to the iPad watching a movie. So the solution doesn't need to be conducive to sleeping. via /r/Parenting http://ift.tt/2jUV7qR