Consider doing the situps after back-centric workouts. Sometimes those bent rows (deads, KB swings, etc.) can do a number on the muscles of your low back. We've found that (for some people) situps directly after a low back stressing workout can decompress your spine.
Now for some of you, putting your back into flexion (as with situps) is aggravating in and of itself. In that case, consider some extensions. Several sets (3-5 generally) of 15-20 superman back extensions could do the trick.
Understand - there is nothing inherently wrong with bent rows (or most other exercises, for that matter). It is just that some of us are particularly affected negatively by certain movements. When this happens, it is good to do some countering moves. Learn which movements are best for you. GPP trainers are always glad to help here. Remember, if you have pain while performing a particular exercise, avoiding the move may not be necessary. Sometimes the moves we shy away from the most are the very ones that would heal us. That being said, there is no point in kicking a dead horse either.
Here is something else you might try -