[Bicycle Bob]

You could still do a lot with clear panels up to the Driver's eye level, and accept that the cockpit opening ends with a rounded obstruction. A gentle lip around the opening might establish better flow. Some F1 cars in the mid 60s met that spec, and used a clear duct- a double windshield - to help throw air over the opening.
A streamlined structure can be added just in front of the roll bar so it can draft at 1/4 the usual drag, and minimal dimensions used. If people want a handle on their roll bars as often seen in pictures, make it longitudinal, or add a finger gap to one spot on the wind splitter ahead of it. Or, maybe it can legally almost fill a gap in a continuous headrest fairing.
I am well aware of the usual wisdom that suspension adds weight and complexity. That's why I demonstrated that it does not have to, except for the considerations in the frame design, always looking for useful flex instead of making everything rigid. If you only need short travel, it gets much easier. It saves the rest of the structure from vibration and shock, even if the driver is comfy enough, and is good practice for the real world. A pan chassis lacks torsional rigidity, but that only becomes important for tuning the oversteer/understeer on a poorly balanced design.
Sharp corners on the body are OK on aircraft, but likely to cause problems in crosswind driving, causing early separation. It is easy to get a smoother curve on Coroplast in 2-D by slitting the inside skin between a few ribs. Blunt the blade tip to make it easy to control and angle the knife to keep the cut edges from jamming.
Bamboo is lovely stuff. It is six times stronger than aircraft aluminum, although it bends six times farther before failing, so it works best in a space frame. Resin and fiber lugs are a good solution to the joining difficulties.