Level 47, you are just about where I am, Vincent being next. The sun is a killer in this game, and although the moon is out longer it still very much impedes me. Getting quality slaves is also tough, you barely see the guys who are shrouded with blood and when you do.. are not in a position to get them.
I learned that one the hard way, always have a spare coffin.
I've lost count how many times i've been taken out by the sun lol.
I managed Vincent by kiting him around a rock. Might be a good tactic for some of the others, so long as you can manage passing adds.
Him and a few other bosses will also fight each other as they move around. A cheap way to get some kills lol.