I do understand the concern about squashing but something I read somewhere (maybe one of Pinky's books) is.... when was the last time you fell out of bed? Even in our sleep we are aware to some extent of our surrounds (although we can't smell) so unless you drink etc it's very unlikely that you will sleep on your baby.
Sleep accidents usually occur when people ignore the safe sleeping guidelines.
Then again if the fear of squishing bubs is stopping you from getting a good night's sleep it might be best to set up a side car or buy one of those snuggle beds - because you need your sleep!!