red flag #1 ... not to be an @sshole, but that was poorly worded.
the others have given you some nice ideas ...
($.01) bulgarian split squats - may be the best overall leg exercise that very few ever do ... it really (and literally) kicks my butt and forces recruitment of the quads, hams, and glutes BETTER than standard bilateral movements do.
($.02) single leg RDLs - ok, these will be felt in the back MUSCULARLY but shouldn't strain the spine significantly ... your @ss will be hating you for days
come to think of it, i really need to rotate these back into my routine ... thanks for the reminder