Trying to mature your character through the clvl / dlvl 20s can be challenging until you can survive even lower depths. One tip here is to use Recall exclusively to return from the dungeon and use the stairs to return back down to the level you left.
Yes, this is more work, and as your clvl increases, the early levels become exceptionally easy; however, it guarantees that you will always enter a level on stairs, facilitating running away.