I think the back pain is due to lack of core strength. Your daily rides are giving you plenty of strength in the legs, but you need to do something for the upper body. I found a few daily push-ups on the edge of a table made my lower back and shoulders a lot easier during the rides. On the edge of a table is better for Clydesdales than on the floor. I dont think your bars are too far forward, but get the top close to saddle level. You will just have the nervous handling of a racing bike due to the steering geometry and short wheelbase.