Last, but not least... It did take like 8 days in the end, not 6, but anyway.
What did I learn from this challenge? I would say, putting artificial restricitions like that made me appreciate more what luxury we have, being able to play multiple strings, haha. One thing that I will keep in mind: Improvise more often to just drum tracks, both rhythm and lead, without any guitar or bass already on the track. Having a strong rhythm as a foundation is actually more liberating than being stuck with a given chord progression.
That being said, here is my last contribution to this challenge, gg. Might do this again some time.