This is one of those 'If you have to ask' things.

Heres a couple of obsticles:

The roof supports the windshield, the A pillar will have to be redesigned. Otherwise it might flyswat the driver from wind force.

The door frames the window, and this guides the glass. door will need redesigned window mechanism.

folding mechinism, actuators, and storage will need fabricating.

Entire chassis will need reinforcing because of loss of stiffness.

Liability concerns if someone ever gets hurt as passenger.

Having assisted on projects like this, I can honestly say its thousands of man hours. Not impossible, but certainly an an advanced project.

John C.