I have an oak floor partly covered with a quite dark stain. In areas I have sanded off the stain and urethaned with clear water-based urethane. Now, I want to put a gel stain over the water-based urethane areas without major sanding to match the darker areas. Then I intend to cover the whole area with water-based urethane. What gel-based stain could I look for to cover the parts of the floor which are lighter but have a thin layer of water-based urethane without a serious sanding?