Glad to help any way I can, Bruce!
For set/rep schemes, my usual protocol is low rep sets (singles through 6 reps max) as the focus when I'm trying to gain, moderate reps (8-12) for my maintenance, and higher reps (15+) for when I'm working to build muscular endurance, up my workload capacity and/or lose fat.
But, as mentioned, you can change things up for doing something like speed doubles with lower max percentage weights as a factor that can help keep you from sliding backward for a while. So, say your squat max is 315, you'd want to do 10 sets of doubles with 205 (65% 1RM), squatting up as explosively as possible for maximum speed up on each rep (usual descent speed is fine, just that the finish of the lift is to be done as quickly as possible). Same can be done for deadlifts, fast pull for speed, normal quick lowering of the weight between reps. Usual thing to do with speed doubles is also to keep rest periods short to about 1 minute (usually not a problem considering the low reps and light workload), and it also help to make some of those lower body sessions go quickly since you can usually get through all 10 sets with rest in 30 minutes or less. If you find that you aren't pulling or squatting each rep with great explosive power, then you may want to reduce another 5-10% off the 1RM amount to get to where you want things to be. If in doubt, check some Youtube videos searching out "speed squats" or "speed deadlifts" for examples - most of the clips are showing people doing box squats (just make sure you click on videos that show people who look like powerlifters, not the ones for things like 'P90X Swiss Ball Speed Squats' or something like that, which could be very different.
So, perhaps just doing the speed squats early in the week, normal upper back, chest, shoulder, arm and core work over the week, and speed deadlifts at the end of the week, and I have the feeling your lower back will be thanking you for the reduction in stress
If anything, try it for a month or two, add 5 lbs. each session if you find that you're blazing through all sets with no problem, and see how it works for you!