All that faff can be avoided* by measuring the voltage drop across fuses / using a DC clamp meter like the Uni-T 210E :-
I tried putting a link in here - but it didn't work - search on the zone for B00O1Q2HOQ
There are other Uni-T models which are better ( and more expensive ) ... I've had one of these for a few years now, and found it better than my Fluke kit from a repeatability point of view
( fecking scary given the price difference
)
....
* = make sure any bonnet switch is held in the closed position, so the car thinks the bonnet is shut, and you can watch the various modules go to sleep - write the times down for future reference ! ( it's exciting this troubleshooting electronics init ?!?!!?
)
I agree that the most likely cause of overnight battery drain is a knackered diode in the alternator - guess you get to upgrade your alternator sooner rather than later