Thoracic: any flexion/extension movement. You can experiment with loading schemes so as to decrease tension on the lower back. A little while back I filmed a few of these:
https://www.youtube.com/watch?v=u6oPC4Y-lK8
Glutes: Any hip-hinge movement; more than likely the ones that do not create distance between the hips and the midline are less likely to create shearing force on the lumbar (that's just my supposition, anyway). Hip-hinges in which the torso starts or finishes on a horizontal or semi-horizontal plane would be a good place to start. Hip Thrusts, glute bridges, glute-ham raises, back extensions.
Unilateral variations can sometimes offer better glute activation. Anteroposteriorly loaded movements can also be kinder on the lower back (someone suggested Duffin's stallions as one example). Here is more info from Bret Contreras, along with a lot of exercise variations:
http://www.t-nation.com/free_online_article/sports_body_training_performance/advanced_glute_training
Hamstrings: Again, hip-hinge movements. Glute-ham raises are a good one (hamstrings activate much more than glutes on these). Exercises that move the hips away from the midline can sometimes be harder with an iffy lower back (i.e. standing goodmornings).
Just my thoughts. If you're squatting high bar and suffering from significant lower-back fatigue, then you're either not squatting high bar with the desirable torso angle, or you might have a significant weakness in the chain. I'd emphasize doing a lot of your compound movements with a more vertical torso, which means high-bar squats, front squats, and sumo deadlifts; these will keep the lumbar from becoming too heavily taxed. A lot of the time, lower-body work capacity is limited by lumbar fatigue more than any other muscle group.