tl;dr: Can anyone point me to a simple process for 'cloning' and adapting an existing module in order to slightly modify its operation?
Backstory: In order to run some simulation exercises (cybersecurity incident response), I've made some small hacks to the Lesson activity to suppress display of scoring and generally make it look less like a "Lesson" and more like interactive fiction. It works tolerably well - well enough for me to consider deeper modifications.
But before I go too much further, I want to avoid my modifications being over-written by the next update. It looks to me as though the best option is to create a new activity module, but I doubt it's as easy as just copying the subdirectory tree and gzipping it up.
I don't want to (don't have the spare time to) go into full developer mode, so is there any kind of gentle guide to getting started at this level?