This is something we’ve come across recently too. Partly out of a drive to more efficiently manage outbound & inbound activities in one place. We don’t use deals and pipelines for initial outreach though. What we’ve found works well so far is creating contact views (and lists) based on a custom ‘Outbound’ or ‘SDR’ property flag - then using prospect lifecycle stages to manage conversations, up until there is an active opportunity, at which point we create a deal in one of our existing pipelines.
This gives us measures like volume of deals created, average SDR flagged deal close rate and average SDR deal value to base performance metrics from.
One thing we have been struggling with is whether to treat outbound contacts as a ‘part’ of the database or transitory. Currently we treat these as transitory, removing from the CRM after 6 months of inactivity. This seems to encourage our sales reps to actively keep conversations alive and more actively work towards engagement.