My husband and I are struggling with the new seats we have for our daughter. They are Britax harness to booster seats. In his truck, it is set up with the seat belt. When she tries to get the seat belt across, it gets tangled in the arms of the seat. Then, the buckle sinks down into the seat of the truck (2005 Toyota Tundra, full size). It is a miserable experience.

Carpool is the worst. He has to get out of the car to get her buckled in properly.

Does anyone who is already using the seatbelt with a high back booster like this have any tips?

Carseat example (pic won't load):