You can always replace the bars with Mountain Drop bars. The drop ends flare out to the sides, just like you say they should.
You seem to indicate you have back flexibility issues. The correct solution is not to "baby" your back, but to actually become more flexible through consistent and safe stretching practices.
Sounds like you are trying to turn a road bike into a wheelchair. Is that how you want to grow old? Coddling yourself so that you become a fragile, inflexible old guy? Better to get flexible and strengthen your core. Then a road bike won't seem as ridiculously uncomfortable as you are making them out them out to be. Do it while you still can.