Just to clarify, I don’t care about my ranking. My ranking will inevitably follow my skill, so my goal is not “to get my rating right”. The problem is finding suitable players for long games. My current rating is 15 kyu, which IMO is on the optimistic side. It has been as “good” as 12 kyu due to timeouts. At that point 15 kyu players simply didn’t select my games from the list anymore.
I just found out that more players did signal this problem. See e.g.
Avoid rating increase after opponent timeout
Allow user to decide whether win by timeout affects rating
FYI, on the Dragon Go Server there is a settings option to not let your rank be adjusted when you won on timeout. So they seem to face similar problems on other Go (and chess) servers as well. I like the solution proposed above a bit more than the DGS one, though.