Carport plan take 2

This is the footprint of my basic idea for the carport/workshop. I have staked out an area 16' wide and 27' long. The portion in foreground is the workshop area. It is 7' of the 27' length. The structure has to be 5' off the property lines, as indicated. There would be a regular automatic garage door in the alley for the car. Already, I don't like this idea. I think the workshop needs to go on the side by the fence. But this is useful, to at least begin to get an idea of the space requirements and to lay down some numbers: 16' x 20' = 320 square feet. 320 square feet x 35 $ per s.f. construction cost =11,200 cost to construct. x 2 property value increase = 22,400 addition to property value. This is my first estimated guess at the cost/benefit analysis for this portion of the overall project. Accurate or not, I have finally stumbled over this first hurdle. I want to be careful to describe how I feel at this time for future reference. I feel like tearing my hair out. But I have made some progress. But the progress is minute compared with the time I have spent making it.