Hi there, my friend bought a little bed you can put in the middle of your bed specially made for babies and co sleeping. So there is no way u can roll on the baby.. She found this worked really well. She bought this from a baby shop.
You can also get little cot-type thingoes that have three sides, that you put right next to your bed. That way, you can't roll onto him, he can't roll off the bed, but you can give him cuddles and he knows you're there. That could be a good option for you.