Not really sure how giving up squats and adding dead lifts is going to help alleviate stress on your lower back. My lower back is taxed a bit furring both exercises, but definitely more so with deads. Deads hit several muscle groups, but it's predominantly a back exercise. Squats hit several as well but obviously more for legs. So I don't know how dropping squats and replacing it with a back exercise is going to be as productive for leg development. I do both, on different days. Could you try a variation of squats that may not hit your back so much? Front BB squats, Hack squats, or sissy squats? None of these are as effective as back Bb squats IMO, but better then nothing.