Are you trying to be Bill Cosby? What should be in your workfile is most likely up to 50 different interpretations. If you are in front of your state board it would be very wise to have original comp photos.
I agree that the workfile is best if it has as much material as possible, MLS sheets, notes of conversations, data etc. Hard to put proof of original photos in it using a digital camera.
RE, yes, an appraiser's signature means they are stating they performed the research and scope of the report. If you guys want to destroy that crediblity you are digging your own graves. The state boards are there to investigate fraud and misleading reports and USPAP violations that affect value, not to question if an appraiser's signature on the report means the appraiser should be believed or not for no other reason than an appraiser got hold of an otherwise good report and decided to challenge it for this reason alone.
If you want to destroy this assumption, then the profession will become a nightmare (more than it already is) For example, you Mich, state many times on the board that you use an assistant. Yet on your reports you sign that you do the research , and I assume disclose the assistant's role, typing reports or calling for verification, whatever their role is. What if anther appraiser gets hold of your report and decides to challenge you on whether your word (Signature) meant what you stated, that you did the analysis and comp selection, and not your assistant? How are you going to prove in court what you did and what your assistant did? And the important question is, why should some random appraiser put you in that position?
What next, a live video cam in everyone's offfice or home office, to provide proof of what they did and who they called when preparing a report? Is that what you want? Do you want live video cams in your car recording your actions, or a GPS tracker to be examined by the client to prove the date of inspection, where you drove, how long you stayed at the subject etc ? (don't laugh, they use GPS trackers in the trucking industry now to time drivers and see where they were, in the old days, the truckers ketp logs, and signed, re, gave their word.)
As the saying goes, be careful what you wish for, you might get it.