The method of turning the INSERT into an UPDATE seems to achieve my goal.
The blank insert generates the ID and I can use that value to perform an UPDATE that can now use that ID for an Image File name.
The reason I am stuck with using the record ID is: the form has very few data constraints, so there are no other usable vales at the form level. Also, the native naming convention of my client's files could be very long and contain spaces and other nasty things.
So, the record ID seemed to me to be the only reliable choice.
If I can't figure out an intelligent solution to the abandoned records issue, that I may have to just use the native file name and standard insert.