Stepups are a good idea since I stay in the same location. (I lift in a busy gym) I do RDL's or a variance of them on my lower back day. Not for my lower back but I feel that I the most responce from them after I tire out my back side with deadlifts.
"Honest answer to Hip Thrusts" I have found that my... ability to... pleasure a woman... has increased since I started doing these. I know its seems sorta of silly since they are called hip thrusts but Im sure you have seen what they look like.. think about how strong that would make your "thrust and grind" action. I dont mean to offend or toot my own horn but this is what I have seen come from these.