I dont Know if it will help you , or not.. or how the low posture that is what a Road Bike is all about, will help the back issues, except perhaps you support More weight with your arms.

I have several bikes with 170,175 and 180 arms . I stuck the M730 180 arms on My trekking bike to give the Illusion the seat post angle was lower than it was ,

though the weight balance was unchanged , until I Bought a seatpost with More Setback. other than that, I switch back & forth with out much difference.

I'm 67 & no carbon fiber bikes. maybe your youthful self image is like that of a sports car, but your body is no longer comfortable in that racer's posture .