BEagle, there is no one with more knowledge than you on all this legislation muddle. There is certainly no one who has worked harder than you on our behalf and mostly from your own pocket.
I cannot believe that there is a single DTO who would require an NPPL holder to do a pre-course and pointless assessment flight. As with all flying it takes as long as it takes. It would also be wrong in my view to make such an assessment from a single flight and then to reduce the pilots credits. If I was an NPPL forced to do this I would walk away and go somewhere else. Should the pilot have not flown for a number of years of course it may take longer than normal. But, this needs to be seen over a number of hours. Most I know demonstrate common sense and complete the silly form at the end of training but prior to the test. As to the pilot the tortoise and the hare comes to mind.
In my opinion you should not make excuses for the discredited bureaucratic mess we are in, you are better than that.