As the others have stated, you CANNOT FORWARD FACE A CHILD UNTIL THE BARE MINIMUM of 1yr AND 20lbs. Its not either or, its both.However the AAP is now recommending that children remain rear facing until the rear facing weight limits of thier convertible carseat, which is 33 or 35lbs. There is not one carseat on the market that allows a child to forward face before 1yr old. READ THE MANUAL of any car seat, if you use it foward facing before 1yr old, it will void your warranty, so if your child is injured in a crash, even if the seat is faulty, and he's foward facing before a year, too bad, you didn't use the car seat to the manufactureres specifications and they are no longer liable. Again NO CAR SEAT ON THE MARKET WILLALLOW FORWARD FACING BEFORE 1yr AND 20lbs.
A car seat is outgrown rear facing when one of these two things happens... there is less than one inch of hard shell carseat above the child's head, or the child goes over the rear facing weight limit of the convertible car seat of 33 or 35lbs. Until then, a child can safely rear face, and its safest to KEEP a child rear facing until at least 33lbs.
Please google 'internal decapitation' and 'extended rear facing' to get some good information. I have two big boys who were both out of their infant seats by 5mos old, and both rear faced until close to 2yrs old, when they reached 33lbs. Their legs will not break in a crash... but even if they did, I'd much rather have a baby with broken legs than a broken neck, wouldn't you?
As for entertainment... He's only 6mos old, take turns sitting in the back seat with him, get some fun toys to hang from linkadoos from the clothes hanger in the back seat (NEVER LEAVE THE HANDLE ON THE INFANT SEAT UP unless SPECIFICALLYU STATED ITS OK TO DO SO IN THE MANUAL!)