Is there door mouldings half way up the door Glenn?
Mask them out, if the mouldings don't go edge to edge on the door roll the tape on the bits that don't so you don't have a tape edge
Scotch the bottom of the door off, make sure your repair area is flat and primed ( just that area )
Flick the colour in thin coats allowing to dry properly between coats, use a heat gun if needs be...
Once your happy the primed area is covered flick the colour up the door trying not to go right up to the tape
Once happy and dry enough clearcoat the bottom of the door
You may have to polish edges where the mouldings don't go to the edge of the doors, bar that should be pretty straight forward

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