[Otto]

If possible, lose the barn door mirrors, replace with smaller, more aero shapes available pretty cheap on eBay, which also has combined mirror/turn signals. Also, note the mirror stalks' cross-section, and convert to teardrop airfoil shape.

A tankbag is handy to carry stuff, and fills in the gap between rider and windshield, where a low-pressure bubble forms and collapses, aka von Karmann vortex. A tankbag in that gap much reduces the buffeting and turbulence there, making for a much smoother and quieter environment inside your helmet. Less drag, too. This is akin to the fairings between cab and trailer on big trucks.

As others have noted, lose the rear hardbags and carry your stuff in your new tail section, or at least make a free-blown teardrop fairing behind the rider, that acts as a backrest for him and a stowage trunk for junk. I suspect your tail section fairing would work as well if only about half that long, and be lighter, cheaper, and more manageable.

On my BMW I may delete the stalk mirrors entirely, and mount mirrors to the windscreen inside the upper edge, sorta like fighter plane mirrors mounted inside the canopy bow, for less stuff hanging out in the breeze.

And, like my BMW R1100RSL, your bike has a big concave gap between headlight and front fender, which acts like a very efficient speed brake. I don't know what BMW was thinking, as the heat to be dissipated is on the boxer cylinder heads, not up in that big hole. Your bike may need the big hole to cool the engine, though. I used a semi-circular section of a plastic bucket, flattened it somewhat into an airfoil shape, and attached it to the front fork struts. This turned that huge speedbrake hole into at least a crude airfoil shape, reducing drag and buffeting significantly. I get about 51 mpg cruising at 80, ~10-15% better than other similar BMW bikes at 70.