Came here to to suggest a similar idea – but in terms of technical I would suggest a very simple idea.
We could simply use WP CLI
And maintain a list of installed plugins URLs from GPLDL – and the run a simple shell script
yet unsure how to handle the required authentification (maybe someone will get some ideas by reading the doc of s2membership – maybe i will – when I coin the time for it somewhere)
have a great day everybody!