You will need a minimum of 12ft sides and if you will have a door you will need to probably go to 14 ft. We just had a 40x50 shed built 14ft eaves, so we can have a 13 ft roll up door. There are many variable in having what you want built, local codes are the biggest factor. I had built a temp tin shelter and had 10ft eaves and it was very close on getting TT in as I had to remove center poles and then reinstall after siting. Out here there are many carport types 8-10 wide with about 12-15ft eaves. These are standard 8ft eaves which have extensions to raise them. Had one at a place I worked for outside maintenance activities, see them around the area for rv storage. Check with your search engine for metal buildings storage in your area to get an idea. My c is about 12 ft high went with higher door in case we ever decide to up grade (doubtful).
example this is pic of double, rvs can be simple single but you get idea. http://www.westernstatesmetalbuildings.com/tucson-metal-carport/