I don't see this as an ethics question as much as it is a perception question for outsiders. I personally don't see any thing in writing that prohibits this. It does raise a question or two from an outside auditor's standpoint. Mainly with Structural work by a fabricator working under AISC certification.
If I was an auditor and I came to a shop and the inspector had dual duties of welding and inspecting, my first question to the fabricator would be... who in this organization would be responsible for inspecting the inspector's production welding and fabricating for final inspection?
Under the new standard Tab 13.1 Assignment of QC Inspections and Monitoring, it states that "they do not inspect their own work".
Is there another CWI that can sign off on this work for you within this organization?
If so, I would get this indivdual to also sign off on your WPQRs just to keep the possible questions at bay.
John Wright
PS. I have wanted to write up my own welding papers too, but I'm the only QC/QA here at this facility and wondered, (as you are) about the perception of this practice.