Interesting to see it as a roller chassis now!
I was thinking for the windscreen, something along the lines of the Quasar based on this picture.
Simple and lends itself to making side entry and aerodynamics without a lot of compound curves.
Plus, the advantages of simplifying the windshields wiper design and effectiveness.
Lately I been eying the Honda SH 150 I as a power plant for mine simply because of it's simplicity for installation, it's water cooled, Fuel injected, it come with larger wheels, has the ability to remain a compact drive train and the fact that it already gets an EPA rated 103 MPG in an open scooter format. Plus it's touted as having enough power to move 2 persons at 65 mph. Should be plenty of motor once you add in a slippery aerodynamic bodywork. I'm not looking for something to break any speed records, but what I think is important is the economy of operation and the ability to keep up in traffic plus the dead reliability of a Honda.
Another simple windscreen approach is that of a section of a funnel as used in the earlier Phaser bikes of the 80's.
They changed the name of these and I can't for the life of me remember what it's called now. Called something like Light Star now!
Not really my cup of tea as I've seen one up close and it was a pain for the driver to enter and egress with the hinged hatch. Even with the massive out rigger wheels it had on it. I can't imagine getting in and out of that thing 4 or five times a day while on a shopping trip.
That's why I'm thinking of side doors using a set of the Lambo style hinges that are so popular with the Custom Car Ricer Crowds. For a 2 seater, one forward door on the left for the Driver and a more rearward door on the right for the passenger. Tying a roof into the head tube like Malcolm Smith did on the Quasar should give it all the rigidity it needs to seat 2 people.
I'm thinking my main frame tube will be an upside down tube that will be reminiscent of a Triumph Tigers main frame tube. It's beefy and simple.
With the door opening to the floor level entry should be simple much like the LIT electric bike designed in California.
Sorry for rambling, I enjoy watching builds like yours and can't help myself in interjecting some of my thoughts. Much of them formulated over many years of running "what if's" through my head at night to go to sleep. I have a notepad on my night stand full of idea I've thought if at night.