travel neck pillows for children

[MissP71]

our 6yo dd is now in a booster seat with no side rests, and whenever we are on long journeys she falls asleep and ends up flopping to the side. has anyone come across any products that prevent this? I was thinking of getting her a neck pillow and see if that helps.. any other tips?
thanks!

is there a particular reason she is just on a booster cushion? dd is nearly 9 and still uses a high backed booster seat as it is safer than just the cushion.

it is mainly when we hire cars on holiday, they never seem to have the backs of the booster seat..