Pete:
I should like to respond to new points you raise in your revised comments.
Although you do not state what bicycle valves you were dealing with in your difficulties in measuring tire pressures, I am pretty sure they must have been Schraders. Although I have not tested these valves yet, I was very much aware of the problems you describe.
One solution might be to use the threaded connector sold by Silca that never allows any air to escape from the tire except that which enters the gauge. Another might be to convert the rim for Presta valves using an adapter that costs less than a $1. If my pump hose adapter is used, there would be no additional cost.
The Presta gauge I describe in my report also never allows any air to escape from the tire except that which enters the gauge. The amount must be negligible because successive readings give identical results as far as can be discerned.
Still whether the amount of air that enters the gauge is small as with the Presta or large as with the Schrader is not important, because their use allow the same pressure to be used for the calibration as for the race-course measurement.
I am proposing the constant pressure method not simply to avoid doing the postcalibration, but to improve the accuracy of certification.
I shall probably do some further tests on three wheel types and the Schrader to see how at constant pressure size varies throughout a day of extreme temperature variation.