Here's a quick drawing with the back adjusted to 2m.

The reason for the elaborate roof on my original drawing was to get around what is happening in this drawing, which is that the roof angles of the sides are different due to the different side widths so the polycarbonate will need to twist slightly to fit the frame, but maybe this will not be a problem.

Is polycarbonate strong enough that I could use one sheet for the entire roof and one for the front without any supports in the middle?