Normandy,
No suggestions for substitutes here, but maybe the reason it's hard on your back is that your form is off. I recommend doing the deadlifts unless you have a specific injury or medical condition that makes it a risky exercise for you. Make sure that you aren't going down so far that your back begins to round (you may want to lighten up on weights for it). I like to think of the action as one of those bird toys that tips forward to dip it's beak into water, then straightens back up. The upper body keeps the same posture throughout (scapular retraction, with shoulders down and back and cheest out), and the only bend is at the hip joint. When coming up (a part of the motion where it's easy to round the back), make sure to lead by pushing your tush in and feeling like there's a string connected to your upper back that is pulling you up.
Deadlifts are great for the hamstrings, glutes and lower back (the last of which they work isometrically). In order to find a substitute for them, you'd either need multiple exercises (a back extension over a medecine ball plus hamstring curls) and/or gym equipment.