My son is 5 years old (will be 6 in June). His shoulders are just under the limit line on his Britax Boulevard Clicktight, so I am looking to get him a new seat. I don't think that he is ready for a seat without a 5 point harness yet due to his maturity level. He has ADHD and can be very impulsive. At his last doctor's appointment in December he measured 48" and 43 lbs. It looks like the Britax Grow With You has the highest harness height, but the standing height limit is just 49". Is it ok to use a forward facing harnessed seat beyond the standing height limit if the child's shoulders are below the highest harness setting?