Don't want to give any medical advice. But you could put the original suspension back on but with eibach lowering springs. Will be lower than standard and should be a much smoother and less harsh ride.
This is the exact set up I have. It rides lovely. I had coilovers on when i first bought the car and couldnt stand it! And I have nothing wrong with my back! Mine sits -30mm which i think looks just right, but I thing eibach do lower spings than that.
The springs are progressive, so you should get a slower stance without compromising
too much on ride quality. It will certainly be a LOT better than coilovers.