You might try subbing 1-legged squats for static lunges. They are VERY effective, moreso than lunges, IMO, and can be done in many ways. You don't even need much added weight to feel the effects. In fact, try them first with NO added weight, and work on ROM.
A one-legged squat series that Mindy Mylrea does in "All About Legs" really hit the glutes (I still feel them two days later!).
Stand with heel on a stability ball in front of you and squat back and down on the other leg (don't use any added weight here until you get the move down).
Move the stability ball to the side and hold your foot on it (you may need to hold the foot slightly forward rather than directly out to the side) and do 1-legged squats that way.
Move the ball behind you, top of foot on the ball, and do the squats, making sure to keep your front knee in good alignment. On last rep of set, stay in the 'down' position and move the ball in and out for reps.
Burn, burn, burn! And all the focus is on the working leg.