I also think that walking lunges are more effective because they are more dynamic and bring more muscle into play. They'd be like combining the dip-down part of a forward lunge with the 'bring-the-leg-back-üp"part of a rear lunge, with some added movement. YOu don't really need a lot of room to do them, just enough room to do two in one direction, then turn and start the return trip with the opposite leg that you used for the first go-round.