First info before the question:
I'm lvl 129, ng+10 with +10 weapons
I rarely see summoning signs
I solo all the bosses for most runs, but it is boring
I picked lvl 129 so i'd be at the lowest level possible that is able to have access to people up to lvl 150, since I thought that was the most common level people stop.
The only two bosses it'd be nice to co-op with are dancer and twin princes.
Question: What level should I be to ensure I will find people to co-op for dancer and twin princes? I am willing to restart if I'm too high lvl.