That's really close to an ideal aerocap shape, I think. Drag vortex generation ought to be minimal.
Edit: This is what I mean. I saw this phenomenon occur with my version 2 aerocap. This is why it'd be better to blend in the rear of the aerocap with the rear of the truck bed and go for a more rounded rear, instead of doing any tapering.
How are you going to secure your aerocap to your bed? I was trying to design something along the lines of a hood hinge, before my version 3 aerocap design process got sidetracked.
The idea was to have the top edge of the cap clear the truck cab, before the hinge allowed the cap to move forward as it opened up, just like a hood.