Nissan Pulsar gen 2, with a swappable notch/Kamm/commando roofline.
About the time you posted this I was contemplating a stake-bed truck with curved top bows for the roof that would rotate forward and down, with wide slots in the tarpauline. When you need the space the tarp would be curved up; otherwise it would be sway-backed between the flat sides.
Same kind of deal.