Another vote for trying something like the Hunter Constantine belt (Tier 1 makes a version as well) with a quality, purpose-built AIWB holster. If you haven’t tried one already, an AIWB-specific holster from JMCK, Dark Star, or PHLster plus the right belt can make all the difference and take AIWB from “nope, not happening” to “I’ll never carry any other way again.” Be sure to try a foam wedge, especially if your stomach isn’t perfectly flat.
I don’t have chronic back problems but carrying with other belts, even good ones, did put enough pressure on my back to be uncomfortable. The Constantine is perfect as it’s stiff enough up front to support a 1911 but at my back it feels like I’m not wearing a belt at all.
Some people have good luck using the Constantine under their pants and a tucked shirt like a PHLster Enigma, which may be useful for your office setting. That doesn’t work for me personally because with my build plus the clothes I wear the Constantine is just a little too bulky up front, but I can see how it works for others.