I have bed rails on both sides of our queen bed, but they don't extend to the length of the bed and the foot board is still wide open on the end.
My 11 mo old uses the bed rail to dangle over (bent at the waist) and pull up to stand (he's not walking yet). I can already anticipate that he could (or will) go head first over the rail, as I have had to hold him by the ankles when he dangles himself over the bed rail.
So, just so you know...bed rails will only buy you minimal time. They are good for keeping your little one from falling off the bed when sleeping, but once awake, it's a no go.
Since I go to bed sometimes 3-4 hours after our LO, I have used very large pillows from one of our sectionals, but a few times already, when our LO has woken up and not made a peep right away, I found him attempting to scale the pillow. It's only a matter of time.
Unfortunately, I think the only solution is to put the mattress on the floor, which I was hoping to avoid too. The crib is right next to the bed, but I also nurse our DS to sleep and am able to cuddle him back to sleep or nurse him when he awakes at night, which he still does 2-3 times. So, the crib has been good for hanging laundry...sigh. I think I might experiment and try to see what happens if I put him in the crib to sleep. We'll see...
I've read other posts where moms will teach their LO how to get on their belly and get down off bed and onto the floor safely, but it depends on the age. For our LO, he isn't at that stage yet, since he can't stand on his own or walk.
I wish there were some netting (like trampoline nets) that could be wrapped around a bed for co-sleepers!