we went thru the same thing with zoey at that age. our bed is an old style California king waterbed, but with a pillowtop mattress not a waterbed mattress. Its very high off the ground and she did a nose dive off the side. It as frightening and we knew she was so mobile it would happen again.
we tried side rails but she crawled right over them. we tried a sidecar and she crawled right out of it (even using a monitor to listen to her sometimes she was just too quiet and too fast!)
finally we ended up buying a fullsize mattress and putting it on the floor of her room (that she'd never slept in). I'd nurse her to sleep in her bed and then roll away. That way if she crawled off the bed she'd be so close to the floor she couldn't get hurt. only once did she wake up noiseless...she crawled all the way down the hall and found me in the kitchen. LOL.
anyway. i'd go in again when she woke at like midnight and nurse her and sometimes sleep with her in there a few hours. Sometimes dh would sleep in there with us, sometimes not. Sometimes i'd go back to bed with dh, sometimes i'd just stay in there with her.
once she started walking sometimes she'd wake up and just get into bed with us when she'd wake up. so we got the best of both worlds..she'd sleep most of the night in her room and we had some privacy, then she'd join us later and we got the joy of cosleeping and waking up with her int he morning.
now she's 2 1/2 and thats still what we do. Dh and I lay with her at bedtime and cuddle till she falls asleep. Sometimes he sleeps with her a while, sometimes i do, sometimes we both get up and spend time together. Then dh and i can have some private time to talk or read in bed. She sleeps from about 8:30pm till about 2 or 3am most nights in there, then wakes up. Sometimes she goes potty, or needs a drink, but most of the time she just walks into our room, climbs up the stepstool we have for her (and the old terrier who can't jump up anymore) and crawls over daddy to sleep in between us. The cutest part is when she says "i'm here now. you can go back to sleep". lol. And we all do.
i like the partial cosleeping. just what worked for us tho