Booster seat model 3 Highland

So my 7.5 year old son sits fairly comfortably in my Golf R backseat. Yes the seatbelt isn't ideal but it's ok across his shoulder.

Looking back when I test drove the model 3 Highland I remember the rear seats are a little more deep. Yes the floor isn't as ergonomic due to the floor being high, but I'm more concerned about depth of the seat and how the seat belt sits.

Are there any booster seats that sit the contours and depth of the model 3 highland rear seat particularly well? Specifically booster seats, not car seats.