I would think the only reason people don't do a single carb setup is that most don't have the ability to fabricate an intake manifold for a single carb.
another idea you may want to consider for a good bobber look is roll the handle bars 180 degrees from where they currently are, then flip your mirrors underneath or try to find some smaller mirrors then put those underneath. I put mine underneath on my drag bars because when they were on the top of the bars, all I could see was my shoulders. Once I did it I got tons of compliments and even had a few people copy it. just have to make sure the mirrors don't hit the tank or your knees. I had forward controls so I was good to go.
I may have to try your technique to lower mine, Those shocks are already 2 inches lower than stock, I want another inch to inch and half lower though.