Hi Skeetaboat - not sure if you will check this, but am having exactly the same problem. My boy is 5 months old now, and he is a very highly strung, sensitive, overstimulated baby, and has always been since birth. Always alert and looking around constantly. Needless to say, he is a shocker to put to sleep and to stay asleep. I am worried that now, he is so overtired, he takes ages to get to sleep, and will refuse to settle after 40mins. Like your baby, he only stays awake for about 40mins before getting cranky, rubbing his eyes and getting really jerky. He was rolling to one side, but is now not even doing that as he is too tired.
Just wondering whether you have had any success, and what you tried?