I legitimately do not know how they've implemented the 'padding' we'll call it. One would assume they would leave extra on the top and the bottom, but I cannot confirm that's what they did. I think the only way I'd be able to really tell would be to run a voltage tap into the inputs of the DC-DC converter hooked up to a small display that showed the battery's current voltage. I would take notes on what displayed when the pack registered full, 50%, and empty. The previous generation packs were full at 116.4vdc, 50% at 102.2vdc, and empty at 95vdc.
I would see if this new 14.4 was registering the same or calling 100% charged a lower value than 116.4, or empty a higher value than 95. And, if it does, what are the new values? I would divide those by 28 because each module has 28 cells and that would give me per-cell voltage values. The previous cells operated between 3.39 - 4.157vdc with a nominal voltage of 3.65vdc. So yeah I'd just be data harvesting.
As a non-technician I don't have the knowledge nor the tools to do what you suggested.
Nonetheless I tried to harvest some data by doing the following:
1) Empty the battery to 0% SoC (drove 2km after showing 0% the first time)
2) Charged the bike full up to 100% and shutting down itself
I (quite) constantly took pictures of the dashboard and the information on the charging station. Quite constantly meaning that I first documented at least every 10% of SoC as long as the kW/Ampere readings of the dashboard stayed the same. After that more or less after each change in the kW-reading of the dashboard. I first took the picture of the dashboard and after that (usually some 6-7 seconds later) of the charging station.
It's a premium with a rapid charger at a 22kW charging station. The charging station gives information about the output in kW and the cumulative output in kW.
The charging was at 17° C. I emptied the battery also at ~17°C and gave as much throttle as was allowed and safe on a mountain pass and highway for the last 40km. However, the last km were downhill and on the city-near highway only 100km/h where allowed.
I put in all the information in a spreadsheet and did some charts as you can see.
I did calculate the kWh-input by multiplying the amount of time with the kW. The smallest amount of time (the time between two changes of the kW-reading) was 24 seconds, the longest (the time between SoC 30 to 40% without change of the kW-reading) was 408 seconds.
Summed up the result was
12.86 kWhThe cumulative output of the charging station was
13.59 kWh.
I know, the calculated result of 12.86 is not absolutely exact but I guess it's not far away from the reality.
The difference to the output of the charging station probably is due to charging losses?
For me this looks like the software is really cutting the amount quite similar to an earlier 14.4-Battery.
The charging curves of the new battery are disappointing compared to the old one (see chart).
The displayed range however is much better with the new battery.
I'm nearly at 64k km and I am doing tours of several days, up to 500km a day and 12 hours on route (including charging time).
That I need to wait much longer to get 95% SoC is really disappointing and I just hope that Zero can and will improve the charging curve further.
I hope they really did implement the padding with some extra on bottom and the top.
The fact, that I did not notice 'leap-mode' even when reaching <2% SoC and that others reported that there is full recuperation even with 100% SoC lets me assume that this is what they have done.
But of course: Voltage measurement as suggested by you would give definitive confirmation.
. Since you are a crack, an OG ... 
