The reasoning behind co-sleeping being a preventative of SIDS is the breathing.
When we breathe out we exhale CO2, this triggers the brain's reminder to take a breath in, to bring oxygen into the blood stream. The mother/parent's breathing regulates the baby's breathing, so co-sleeping babies rarely have those moments that non-co-sleeping mothers report where the baby stops breathing for a few moments before taking a breath in.
It is thought that one of the factors in SIDS is the baby not breathing IN again after an exhalation, rather than suffocation or sleeping on the tummy. I can't remember where I read that, but I DID read it!
Couldn't tell you about the props and gadgets you can get, cos I never got them, sorry!