For work with corroflute (I assume like coroplast) that looks really good. The slab sided one was probably less work? Nice surface finish though—is that like coroplast with an aluminum skin?
The teardrop aerohead posted is ideal, then there's those rules. The teardrop has maximum width at 30% of the length. You can truncate the last 10%, a Phantom tail. The rear axle could be at 60% plus or minus, with reduced track the further back it is.
This shows a flat floor with a half-exponential horn replacing the flat rear truncation. It provides space for the rear wheels.