I commend your effort and comprehensive write up but this seems a bit of an extreme job to achieve this result.
I have disabled start/stop on my vehicle using VCP, this does it electronically in the ECU and is extremely easy to carry out, i have been unable to recreate the results using VCDS but have yet to apply myself to this
There is a device you can buy for circa £30 of ebay that connects to the back of the switch and will simulate a button press everytime the vehicle is started, yes theres an expense to it but will save time routing/connecting cables which i suspect will be beyond the average user ?
Sorry im not trying to talk down your mod i actually think its pretty ingenious but for the average forum member i think there are better ways to go about it