Never did get an answer to this problem - in the end I opted for slightly different workflow.
For my first project I had recorded MXF on the camera as an extra backup. However under the circumstances I used these as a proxy for the editing process (in Premiere) then imported the project into Resolve - replaced the MXF files in resolve with their Canon Raw couterparts did a basic color correction and exported the project (clip by clip) as DPX files, which I then brought back into Premiere for the rest of my post work flow (green screen material). Then back into resolve for the Grade.
My second project was somewhat more substantial and required greater flexibility so I actually 'developed' pretty much all my raw footage into DPX (using the Canon Development software) - it was honestly a time consuming process - there was a lot of footage to process - (not helped by the fact that Canon Development software is really clunky) and obviously more than doubled my storage requirements but allowed me more flexibility in the edit.
To the best of my knowledge still no solution to the RTF format issue in Premiere Pro, however hope this helps. If you'd like the specifics of my process feel free to get in touch, it wasn't quite as straight forward as I'd hoped but ultimately possible.
J