[Bicycle Bob]

Thanks for posting, Ray. Kudos on going lightweight. I don't go to Facebook for anything, since they pretty much destroyed the functioning listservs without replacing their usefulness. As far as I can tell, nothing I posted there was ever seen, probably because I had not done whatever it takes to target my ads.
With the rear engine, I think you will have problems with crosswind stability, and they will get far worse if you add fairings to the front wheels. Those are currently adding about 50% to the drag. Beware of the fairings being unstable themselves, as the most obvious shape puts the CP ahead of the kingpin axis. If you have to, you can just offset the kingpins and spindles to get trail for both steering and aero instead of using a caster angle. It works fine.
You really need to do a coast-down test, and find out what your power requirements are. Timing several points lets you separate out rolling and aero drag. It would also be nice to get the weight distribution and CG height, which can be calculated by weighing the front and rear with each end lifted in turn.
There is a great account of the test results on a WWII fighter aircraft, from the original shape to one with cooling vents, guns, and other little details. The drag doubled. The devil is in the details, covering all spokes and managing the flow in shear between moving and stationary parts, minimizing or fully sealing openings, gently ducting and closely regulating the cooling air, etc. Laminar flow is very seldom present on road vehicles, as the slightest blemish or irregularity trips it to regular turbulent flow, spreading out at 30 deg from there back. The back wheel looks nice, but expensive on fuel.
The windshield/roof will bake you on a sunny day, and the angle somewhat impairs vision, especially if there are any manufacturing defects. It will need a defroster, being hard to reach, and an outside wiper that won't scratch it with road grit.
If you are using 17" wheels, you might be able to pry loose a set of Michelin solar race car tires, which would probably halve your rolling drag. Maybe we should set up some sort of petition or PR campaign to make those generally available.