I think I'm much closer to answer my question above than ever before.
The simple method to play the stock campaign can simply be to install TWoS and then replace all the files from a good stock game setup that will revert to original OH2 campaign. The files to replace come from this mod:
OHII v2.5 - No Stupid Tonnage Bar_Free Style Campaign
After the replacement the campaign should play out like in stock for those 'nostalgics' I have mentioned.
First, thanks all of you for your patience in reading all this, I appreciate all your feedbacks

Now, just 2 final questions:
- In TWoS, is it possible to make it so to play the Tutorial of the stock game or at least the video sequence of it + an adjusted player guidance?
- In TWoS, is it possible to re-introduce bunker video sequences from the stock game (like the one at the end of the tutorial after docking)?
Thanks,