*** SUCCESS ***
Okay, it went like this. I tried to use the --verify option in Astrometry.Net against a FITS bintable containing the x,y, flux values for a bunch of sources detected in wide angle (20 degs) imagery captured with an uncooled camera and a 24mm Canon camera lens.
The idea was that a refined AN solution would provide more reference stars in the .corr file which would make it easier for me to distinguish dim stars from potential movers, improve the error residuals on the polynomial used to cope with the lens/field distortions and, also, support an improved Zp estimation (I use only stars that are not of extreme colour nor contain any pixel that is above the point at which the sensor becomes non-linear in response).
Dustin suggested a couple of approaches we might take and, after several loops/iterations we established a way that worked simply and reliably.
We probably would have iterated faster if there had not been a significant time zone difference and I had not had the mental agility of a stunned gerbil, due to a severe cold.
TL:DR It works!
Looking at the results, I have increased the number of reference stars identified by ~80%, my median positional error has dropped and I have yet to test the Zp improvement - but the estimated error bars look very hopeful. So, a win, win, win!
First, undertake the usual plate-solve routine - in my case:
solve-field sourcesbintable.fit --tag-all --overwrite --no-plots --crpix-center --width 696 --height 520 --cpulimit 60 --tweak-order 2 --downsample 1 --scale-units degwidth --scale-low 0.1 --scale-high 180.0
followed after it has solved, by:
solve-field --verify sourcesbintable.wcs sourcesbintable.fit --width 696 --height 520 --tag-all --continue
On the small image I gave it, the extra run time was less than 1s on a 2.8GHz laptop and, as I was running it via a Windows WSL session, theres also a Ubuntu session startup time to be factored in.
Remember though this is for running using a FITS binary table of detection info. If you are instead running against a normal 2D image, its much easier and less fiddly. My usage is a little niche.
Thanks to Dustin for his patience (again).