Another bad back sufferer here. Sciatica.
During my weekly visits to the chiropractor, I need to empty my pockets, so I have been dumping everything into an old fanny pack that I carry like a sling bag. That's not ideal, but something.
For everyday carry I have moved to a S&W 43c in a pocket holster for my Rule 1 gun.
All the old guys I shoot 22 rifles with tell me I should do away with the belt and get suspenders. My chiropractor says many people who try that find improvement.
I'm experimenting with just not wearing a belt for now. It seems the pressure on my back from the belt worsens things. I can feel the difference in just a few days. For now I'm going to not wear a belt and have the bare minimum of items in my pocket and all other stuff goes in the sling bag. Notice I said sling bag instead of fanny pack because it's more cool.
I'm also experimenting with ultra light handgun AIWB with a clip holster clipped to the waistband of my trousers without a belt. I think it could work if your pants fit around the waist.
I'm interested to see what others come up with.