I find walking Lunges work the lower body pretty well and spare the lower back. I put on knee pads, grab a 50 lb DB or KB in each arm, and work up to doing sets of 25 yards/meters.
Then grab a bigger bell with 1 arm and do uneven suitcase carries for sets of 50 yards. Both sides.
Then grab a very small KB and do single arm bottoms up KB carries for sets of 50 yards (in the cleaned rack position). Both sides.
Maybe afterwards use a light KB and do sets of 8-15 of single leg deadlifts.
If you want to train ballistics, go into yiur yard or driveway and do sets of 3 with long jumps. The mechanics of the jump should look very similar to a KB Swing.
You can also do short 40 yard/meter sprints to get the "ballistic" training. Start slow.
Then consider your lower body well worked while also giving your lower lumbar time to heal (a few months).
Regards,
Eric