Thanks to all of you for your replies.
I think we have got to stop more often. We have limiting circumstances in terms of nice places to stop. We drive from a very 3rd world country next door to South Africa to RSA so the road is very rural with no picnic spots, plenty roadworks and no decent fuel stations with gardens and picnic spots. In fact, almost none.
Also, without trying to find excuses, we don't like to drive at night because its a bad road with plenty inexperienced drivers and narrow roads, so its not always the safest bet.
We would not travel this road if we had a choice but have to to get to a 1st world town in SA to stock up, do doc appointments etc. Just in case you think we choose this and are cruel to our baby! ;-0
He doesnt scream thank goodness, just niggles and moans and gets frustrated. I am sure facing forward will help and now that he's 9 months and legal to face forward, we will buy him the new car seat for that.
I guess there is no real solution... maybe new toys esp for the trip might help.