What would you do for an 8 year old boy who is too wide for boosters. Today he tried all of my boosters. He just fits in the Monterey, but the seatbelt doesn't fit under the arms of Monterey they are forward of the arms. He sat in the Harmony youth booster or rather he sat on the arms of the youth booster. He tried the backless turbo booster and the seatbelt wouldn't go under the arms due to his legs. It also stuck on him when he tried to stand up. Our evenflo amp seemed to have the best fit but it was still a little tight getting the seatbelt between the arm of the booster and his leg. Oh the Cosco topside was a no go too. He is short but very round for his age. He doesn't ride in any booster in his mom's car because he is 8years old (I think he hasn't ridden in a booster since he hit 80lbs which was probably before he was 8). I would like for him to ride in a booster in my car because the seatbelt doesn't fit him without one, but then he doesn't seem to fit any boosters. Is there a really wide booster out there? He will ride with us occasionally so I don't want to spend a lot of money. Even if it isn't perfect fit should I just go with the amp?