Canvas Roofed Teardrop...

Has anyone constructed a teardrop with a canvas roof? I have been thinking a lot about it but since I haven't seen one done I am having a very hard time imagining how to upholster the canvas so that it will attach to the tear and not allow any water in.
My main reason for this idea is to get rid of some weight and so I won't have to build a hatch.
If anyone has done this or has any suggestions then PLEASE post any input.
My main reason for this idea is to get rid of some weight and so I won't have to build a hatch.
If anyone has done this or has any suggestions then PLEASE post any input.