I know nothing about boosters but am considering a booster as a second seat for my 6 year old. I'm looking for something lightweight and easy to move from car to car as this will be a backup/secondary seat for short trips in dad's car or grandma and grandpas cars. (2011 jeep Cherokee, 2008 corvette, 2008 escape and 2015 suburu outback). Kid in question turned 6 in September and is about 46 in tall and about 45 lb. he normally rides in a harnessed Britax frontier 90 about 98% of the time and a ride safer travel vest that he will outgrow soon as our backup. Any info on boosters would be greatly appreciated! I know that wee are HBB and no back boosters, but past that I honestly know nothing about them.