Just another note,
If your roof is not yet cut out. on mine I made it wider and longer with formed 'gutters' on the sides.
This way water does not drip down inside of the doors and on the longer , very little rain actually gets to the front and rear windows in normal circumstances.
I allowed about 4" frt and aft with maybe 1 1/2" on the sides.
Also I padded the inside prior to attaching the roof with metal screws to the frame. (ie, sandwitched the padding)
This helped insulate, but best of all cut down any 'drumming' noises.
Again, looking good!