Brigitte, you might be interested in a manual my colleagues and I wrote, Engaging Women in Trauma-Informed Peer Support, https://www.nasmhpd.org/sites/..._REVISED_10_2012.pdf We have also developed and delivered dozens of 2-day trainings on Trauma-Informed Peer Support.
As to your question about research about IPS - the reason is that, until recently, no one has funded research/evaluation of IPS, which, as I'm sure you know, is expensive. I'm currently about half-way through a 3-year study of Intentional Peer Support funded by the US National Institute on Independent Living and Rehabilitation Research (NIDILRR). As Angie noted, IPS is a trauma-informed approach to peer support.
Darby Penney