For a very tall 5yo who is already even with the belt guide on the TB at its highest setting... Parkway, Monterey, or Vivo? Which is the easiest to transport between vehicles/my upstairs closet and easiest for other people to use? (Although my 5yo is just as bad as I am and she coaches everyone she rides with, so I'm not too concerned there.) It needs to work in vehicles without head support. I'm ready to buy, but I keep changing my mind!